LS-5 w/ A/C shroud extension ???... again

**James B.** · August 27, 2013, 10:28 AM

Re: LS-5 w/ A/C shroud extension ???... again

Tom,

For my 1972 454 w/ A/C, the service replacement shroud and shroud extension which I had purchased separately in the early 1980's from a Chevrolet dealer both fit together perfectly. The shroud is part number 3956119 and the shroud extension is part number 3974013 (not 3974014).

Jim

**Joe L.** · August 27, 2013, 10:59 PM

Re: LS-5 w/ A/C shroud extension ???... again

Originally posted by James Burrell (8408)

Tom,

For my 1972 454 w/ A/C, the service replacement shroud and shroud extension which I had purchased separately in the early 1980's from a Chevrolet dealer both fit together perfectly. The shroud is part number 3956119 and the shroud extension is part number 3974013 (not 3974014).

Jim

Jim------

GM #3974013 is the under-chin air dam not a fan shroud extension.

**Joe L.** · August 27, 2013, 11:47 PM

Re: LS-5 w/ A/C shroud extension ???... again

Originally posted by Lynn Larsen (46337)

Like so many, the extension on my car has been missing. After hearing how the repro's are difficult to get fitted into place I decided to be patient and find an original. I was lucky enough to do that at Carlisle this past weekend. Once home I found some time and tried to install the extension but found that the holes simply didn't line up.

The shroud is a 3956119 and the extension I picked up is a 3974014. From what I've read in the archives, and other places, these are a matching set and correct for a '72 LS-5 w/ A/C. If I'm wrong please correct me so I can try to find the correct parts.

After messing with it I had a thought, were these two parts placed in a jig of sorts, drilled, had the t-nuts inserted and screwed together as one piece for each car? If this is the case is it a reasonable to think that a given shroud and extension are unique to each other and may not be interchangable with other shrouds and extensions??

I've attached pics of the holes in the extension, the holes seem to be dimensionally uniform and appear similar to pics that I've seen on other extensions. I've also posted pics of the holes in the shroud, note how the holes are not dimensionally uniform. One is higher than the other, note the distance from the lip to the hole on each side. This is what appears to be my fittment issue. Looking forward to your thoughts. Thanks!!

[ATTACH=CONFIG]47858[/ATTACH][ATTACH=CONFIG]47859[/ATTACH][ATTACH=CONFIG]47860[/ATTACH][ATTACH=CONFIG]47861[/ATTACH]

Lynn-----

The pieces were assembled at St. Louis and I do not think they were custom-fitted.

As far as the correct extension goes, I'm not sure. There may have been a different shroud used for early 1970 with LS-5, this shroud being GM #3974015. I believe that is the shroud used with the 3974014 extension. To be honest, I've never seen one of these 3974015 shrouds. GM says that the 3975015 was replaced in GM #331869 in December, 1973. However, while the 3974015 was once cataloged for SERVICE for 1970-71 Corvette LS-5 applications, I can't find that the 331869 was ever so-cataloged. I don't know what to think on this one.

What I believe is that the GM #3974014 extension was designed to work with the GM #3974015 shroud. I believe the GM #3956119 shroud requires the GM #3956089 extension.

I can tell you this much: I have several NOS GM #3956119 shrouds and 3974014 extensions and the GM #3974014 extension will not fit the 3956119 shroud.

**Tom L.** · August 28, 2013, 09:32 AM

Re: LS-5 w/ A/C shroud extension ???... again

Joe,

My car has the GM #3956119 shroud in it and I can't say that it's original to the car so I won't. As part of my search I looked at every big block C3 that I could find at Carlisle, with or without A/C. Every one of them had the GM #3956119 except for a '73 BB I saw, didn't write down the number for it though. Between that and an old comment of yours, in 2002 (old, I know), I felt certain that the shroud was correct and that the 3974014 extension would be correct, seems I'm wrong. Here's the link and comment:

"Tom-----

GM #3956119 is the only fan shroud ever used for 1972 Corvette big blocks, with or without A/C.

The fan shroud extension for non-AC cars was GM #3956089. This extension was discontinued in 1983. I believe that it is available in reproduction, though, from sources like Dr. Rebuild.

The extension used for 454 cars with A/C was originally GM #3974014. This shroud was discontinued in August, 1973 and replaced by extension GM #336152. The GM #336152 extension was the PRODUCTION extension for 1973 Corvettes and was designed to be used with the 1973 shroud, GM #339175. The 336152 extension became the SERVICE part for 1972 applications only when the 3974014 was discontinued. What fitment problems that it might present when used with the original 3956119 shroud I do not know. You may have discovered them, though.

I think that what you need is a reproduction of the 3974014 extension."

Now I'm NOT calling foul and I didn't go into hock for the piece so it's not a huge deal, it just seems that there's very little solid information about what IS correct. If you can say, which the AIM doesn't, what would be the correct shroud for a '72 LS-5 w/ A/C?? Perhaps I have an incorrect shroud, certianly possible. Also, what would be the application for the 3974014 extension? Seems I may have to find a new home for it. Thanks for the help.

**Tom L.** · August 28, 2013, 09:34 AM

Re: LS-5 w/ A/C shroud extension ???... again

Jim, When I saw your number when you sent it to me I also looked it up. Perhaps way back in the 80's when you were "overcharged" for the piece someone typed or wrote it down wrong. Not sure why yours fits and mine doesn't. You described the storage situation of your car, but are you able to get to the extension to check the number? No big deal if you cant.

**Joe L.** · August 28, 2013, 02:01 PM

Re: LS-5 w/ A/C shroud extension ???... again

Originally posted by Lynn Larsen (46337)

Joe,

My car has the GM #3956119 shroud in it and I can't say that it's original to the car so I won't. As part of my search I looked at every big block C3 that I could find at Carlisle, with or without A/C. Every one of them had the GM #3956119 except for a '73 BB I saw, didn't write down the number for it though. Between that and an old comment of yours, in 2002 (old, I know), I felt certain that the shroud was correct and that the 3974014 extension would be correct, seems I'm wrong. Here's the link and comment:

"Tom-----

GM #3956119 is the only fan shroud ever used for 1972 Corvette big blocks, with or without A/C.

The fan shroud extension for non-AC cars was GM #3956089. This extension was discontinued in 1983. I believe that it is available in reproduction, though, from sources like Dr. Rebuild.

The extension used for 454 cars with A/C was originally GM #3974014. This shroud was discontinued in August, 1973 and replaced by extension GM #336152. The GM #336152 extension was the PRODUCTION extension for 1973 Corvettes and was designed to be used with the 1973 shroud, GM #339175. The 336152 extension became the SERVICE part for 1972 applications only when the 3974014 was discontinued. What fitment problems that it might present when used with the original 3956119 shroud I do not know. You may have discovered them, though.

I think that what you need is a reproduction of the 3974014 extension."

Now I'm NOT calling foul and I didn't go into hock for the piece so it's not a huge deal, it just seems that there's very little solid information about what IS correct. If you can say, which the AIM doesn't, what would be the correct shroud for a '72 LS-5 w/ A/C?? Perhaps I have an incorrect shroud, certianly possible. Also, what would be the application for the 3974014 extension? Seems I may have to find a new home for it. Thanks for the help.

Lynn------

I used to think that the 3974014 extension was the correct one for 1970-72 Corvettes with LS-5 and 3956119 shroud. However, I learned after trying to fit one to a 3956119 shroud that it didn't fit correctly.

GM parts information shows that the GM #3974015 shroud was used for 1970-72 Corvettes with LS-5 and A/C. However, I've never seen a shroud with that part number. Of course, that does not mean there were not any. In any event, I now believe the 3974014 extension was designed for use with that 3974015 shroud and that's why folks (including me) have problems fitting the 3974014 extension to a GM #3956119 shroud.

I now think if a car has the 3956119 shroud, original or not, with A/C or not, then the 3956089 extension is what's needed.

I've also got to say that GM information on this is very confusing and somewhat dubious as to accuracy.

Does anyone out there have a 1970-72 Corvette with LS-5 and A/C that has a GM #3974015 shroud?

**Hank H.** · August 28, 2013, 04:42 PM

Re: LS-5 w/ A/C shroud extension ???... again

I have a #3974015 shroud that I purchased about 6 months ago on e bay as a replacement for a 72 LS5 with AC. Prior to installation, I decided to live with the current shroud which has a piece broken out. It seemed the judging deduction was more palatable than the process of replacing the shroud. This #3974015 is a lighter gray (mine has some black paint on it) than the original on my car although I have every reason to believe it is a correct fitting shroud as there are several references to this part number in the posts above and in the discussion board archives. If anyone needs one, please contact me.

**Paul O.** · August 28, 2013, 07:05 PM

Re: LS-5 w/ A/C shroud extension ???... again

Hank

If you can post a photo of the 015 shroud would be a great help. Have judged a few cars with with a lighter then what we think as normal production color black. If memory service me they were early production 1970 big block cars but that is just from memory no photos for help. But for sure they were 70-72 cars and those appeared to be original to the car no deductions were made.

**Tom L.** · August 29, 2013, 07:10 AM

Re: LS-5 w/ A/C shroud extension ???... again

Hank, is the shroud in your car a #3974015? If so, does it use the 3974014 extension? Sending a PM

**Tom L.** · August 29, 2013, 07:17 AM

Re: LS-5 w/ A/C shroud extension ???... again

So it sounds as if the exact use for the 3974014 extension can't be identified either, strange.

To add to Pauls question, is anyone using the 3956119 shroud and the 3956089 extension for a LS-5 w/ A/C? AND does it interfere with the tipped fan?

**James B.** · August 29, 2013, 10:47 AM

Re: LS-5 w/ A/C shroud extension ???... again

Tom and Joe:I did a little more researching through my records and did confirm I had purchased a service replacement shroud (part number 3956119) from Chevrolet in 1981. However, I stand corrected regarding the shroud extension. I mistook the "under-chin air dam" (part number 3974013) as the shroud extension (as the receipt simply indicated "extension"). As I did not find a receipt for a shroud extension, it appears that I had reused the original shroud extension and attached it to the service replacement shroud (part number 3956119). I don't recall having any difficulty getting the two parts to fit together correctly. I will try again to locate a number on the original shroud extension and post some photos.

**Hank H.** · August 29, 2013, 02:28 PM

Re: LS-5 w/ A/C shroud extension ???... again

Lynn, my 4015 shroud is not on the car, and I don't have an extension with it so I can't really answer that question. I will post photos later this afternoon.

**Hank H.** · August 29, 2013, 04:23 PM

Re: LS-5 w/ A/C shroud extension ???... again

Paul and all. Here are some photos of the 015 shroud. It has some black paint on it, but you can see the lighter gray color in exposed areas.20130829_151241.jpg 20130829_151306.jpg 20130829_151319.jpg 20130829_151448.jpg

**Hank H.** · August 29, 2013, 04:30 PM

Re: LS-5 w/ A/C shroud extension ???... again

Paul and all. Here are some photos of the 015 shroud. It has some black paint on it, but you can see the lighter gray color in exposed areas.20130829_151241.jpg 20130829_151306.jpg 20130829_151319.jpg 20130829_151448.jpg

LS-5 w/ A/C shroud extension ???... again

LS-5 w/ A/C shroud extension ???... again

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