Original 67 Driveshaft?

**Joe L.** · April 4, 2015, 04:21 PM

Re: Original 67 Driveshaft?

Originally posted by Howard Heinsohn (43056)

Restoring a 67 and found the driveshaft had the longitudinal blue seam...evidence of weld. Has a green painted # looks like 8963862 which made me think this may be service replacement? The driveshaft has a green band painted around the O.D.with just a spec of orange. However, right below the green # there is the number 395 marked in white crayon. This number is on the Tank Sticker in pencil, above the gas tank in white crayon underbody, and marked on fiberglass below the battery passenger side. Is this original? Or service replacement?

[ATTACH=CONFIG]60129[/ATTACH][ATTACH=CONFIG]60130[/ATTACH][ATTACH=CONFIG]60131[/ATTACH][ATTACH=CONFIG]60132[/ATTACH]

Howard-------

The number is 3963852. This is a SERVICE replacement driveshaft for 1963-67 Corvettes as well as 68-70 Corvettes with manual transmission. Other than the part number I don't think there's any discernible difference between the original driveshaft and the 3963852. Both the original and the 3963852 were welded tubing, not seamless tubing.

**Dennis O.** · April 4, 2015, 04:30 PM

Re: Original 67 Driveshaft?

I'll say up front that I don't know much about this. That being said, it looks like the job number is written on the drive shaft. (It matches the number on the tank sticker, and a couple of places on the body.) Could this car have been previously restored? That's the only reason I can come up with for this. Just seems odd to me.

**David L.** · April 4, 2015, 04:38 PM

Re: Original 67 Driveshaft?

The difference is the wall thickness of the tube.

According to my research the 1963 to 1969 (and possibly early 1970) driveshafts is GM # 3830618, 2.00" dia., 29.90" c/c u-joints, 0.095" wall thickness, overall length 31 25/32".

The 3963852 driveshaft was the same except that the wall thickness is 0.120". The part number change took place in Jan. 1970 as per Chevrolet Parts History for service parts but who knows when the change actually took place on the assembly line.

The 1968-1970 driveshaft for models w/TH400 is GM # 3924148, 2.00" dia., 29.50" c/c u-joints, 0.095" wall thickness.

Dave

**Joe L.** · April 4, 2015, 07:20 PM

Re: Original 67 Driveshaft?

Originally posted by Dennis Odoms (13959)

I'll say up front that I don't know much about this. That being said, it looks like the job number is written on the drive shaft. (It matches the number on the tank sticker, and a couple of places on the body.) Could this car have been previously restored? That's the only reason I can come up with for this. Just seems odd to me.

Dennis--------

This could not be the original driveshaft installed in a 1967. For one thing, the 3963852 did not even exist in 1967. Second, the part number stenciled on original driveshafts was the part number for the assembly which included u-joints. This assembly was never available in SERVICE.

**Dennis O.** · April 4, 2015, 07:53 PM

Re: Original 67 Driveshaft?

Originally posted by Joe Lucia (12484)

Dennis--------

This could not be the original driveshaft installed in a 1967. For one thing, the 3963852 did not even exist in 1967. Second, the part number stenciled on original driveshafts was the part number for the assembly which included u-joints. This assembly was never available in SERVICE.

Please read my question; in no way am I trying to infer that this is the original driveshaft. I am merely curious as to how it got a matching job number on it. The only thing I can think of is a previous restoration. Can anyone else think of any other way this could happen?

**Joe L.** · April 4, 2015, 08:19 PM

Re: Original 67 Driveshaft?

Originally posted by Dennis Odoms (13959)

Please read my question; in no way am I trying to infer that this is the original driveshaft. I am merely curious as to how it got a matching job number on it. The only thing I can think of is a previous restoration. Can anyone else think of any other way this could happen?

Dennis------

I did read your question. I realized that the main thrust of it was in regards to the job number. However, one could also take from your question that you thought there was at least some possibility the driveshaft was original. I wanted to make it clear that the driveshaft now in the car could not be the original driveshaft under any circumstances. Given that the driveshaft could not be the original, the answer to how the job number got there becomes obvious: somebody post-St. Louis put it there. Whether it was done as part of a restoration or for some other reason, we'll probably never know but it doesn't really matter too much. If it was done by a restorer, he was pretty inept. Leaving a stenciled part number on the driveshaft that is incorrect and could not possibly have been on the original driveshaft while going to the effort of adding the job number to simulate originality is pretty dumb. Especially since he could have easily removed the incorrect number and stenciled on a correct one.

**Gene M.** · April 4, 2015, 09:19 PM

Re: Original 67 Driveshaft?

Is it possible the job # is original and the stencil part # is not?

No way to check the wall thickness of the tube.

**David L.** · April 4, 2015, 10:01 PM

Re: Original 67 Driveshaft?

Originally posted by Gene Manno (8571)

No way to check the wall thickness of the tube.

You could check the wall thickness indirectly but you need a 3830618 driveshaft for comparison.
If the length is 29.9" c/c u-joints then the 2" dia. tube must be 26" or so (close enough for this purpose).
A 26" long 2" dia. steel tube with a 0.095" wall thickness would weight about 1.93 lb./ft. X 26"/12" = 4.2 lb.
A 26" long 2" dia. steel tube with a 0.120" wall thickness would weight about 2.41 lb./ft. X 26"/12" = 5.2 lb.
Therefore the 3963852 driveshaft would weigh about 1.0 lb. more than a 3830618 driveshaft.

Dave

**Gene M.** · April 5, 2015, 09:19 AM

Re: Original 67 Driveshaft?

Originally posted by David Liukkonen (3775)

You could check the wall thickness indirectly but you need a 3830618 driveshaft for comparison.
If the length is 29.9" c/c u-joints then the 2" dia. tube must be 26" or so (close enough for this purpose).
A 26" long 2" dia. steel tube with a 0.095" wall thickness would weight about 1.93 lb./ft. X 26"/12" = 4.2 lb.
A 26" long 2" dia. steel tube with a 0.120" wall thickness would weight about 2.41 lb./ft. X 26"/12" = 5.2 lb.
Therefore the 3963852 driveshaft would weigh about 1.0 lb. more than a 3830618 driveshaft.

Dave

Sounds logical as long as the rust has not affected the .120" wall tube to the tune of 1 pound!

**Dennis O.** · April 5, 2015, 12:18 PM

Re: Original 67 Driveshaft?

Originally posted by Gene Manno (8571)

Is it possible the job # is original and the stencil part # is not?

No way to check the wall thickness of the tube.

At least someone is thinking "outside the box". The whole thing sounds curious to me, which is why I raised the question. Could this be a badly botched early restoration? (I have the original driveshaft in my '68, and IIRC, the stenciled numbers don't look like this; been at least 15 years since I last saw it, though). I guess my original question should have been directed at the OP; Howard, does the car show signs of a previous restoration? Maybe a long time ago and not such a good job? I think the only thing to do would be to weigh this driveshaft along with a couple of known others of both types to try to get a definitive answer. Also, I wonder why a driveshaft would have been replaced in the first place (and that one seems to have been there for a while).

As an editorial, I would like to state that I never intended for this to become a topic of major conversation; it just struck me as odd and I was wondering if anyone else felt the same way. I think most people would have merely cleaned it up, re-stenciled the proper number and re-did the colors and job number according to what was on there and called it good.

**Howard H.** · April 5, 2015, 11:01 PM

Re: Original 67 Driveshaft?

Thanks for the info on the driveshaft. Talking with the PO he had purchased the car in 1974 and did very little to the car since. I've emailed him to see if he had any information on the driveshaft replacement. I figured it was service replacement with the green numbers. I'll check the wall thickness with an ultrasonic tester and compare to an original.

**Dennis O.** · April 6, 2015, 10:15 AM

Re: Original 67 Driveshaft?

You folks have to forgive me, but this has been bugging me for the last couple of days. Joe Lucia's comments started me thinking about this, and Gene Manno's post turned on the light bulb in my head. What we have here is a part that has some assembly line markings on what appears to be a service part. How can this be? While it may at first seem logical that the part number has to be correct, a little thought leads me to believe that the part number is wrong while the job number is original. Why do I say this? First, we have to realize that back in the '70's, things were a lot different than they are today. The NCRS was in its early infancy. Certainly, there were no reference books available to the general publc like there are today. Probably the only source that an enthusiast had for part numbers was his friendly neighborhood Chevrolet dealer. As to job numbers, I doubt that 1 in a 1000 Corvette owners in those days knew that they even existed. Add to that the fact that they are in obscure, hard to see locations and most often obscured or illegible, leads me to believe that they were not even in play in those days.

Here's the most likely scenario I can come up with for this situation. Lets say Joe Schmoe bought himself a used Corvette from the local Chevrolet dealer in the early '70's. After driving it for a couple of years, he starts hearing a strange sound coming from underneath the car. After a couple of days of this, he puts the car up on jackstands, checks a few things out, and finds that the problem is a bad U-joint in the driveshaft. He pulls the driveshaft and removes the faulty U-joint. While he is doing this, he notices the driveshaft, while dirty and covered with road debris, has a partially obscured part number stenciled on it. "Hmmm", Joe muses, "I think I'll clean this up a little before I put it back in". He then goes back to the local Chevrolet dealer to pick up a new U-joint, while he's there, he asks the parts man, "Say, what's the part number for the driveshaft on my 'Vette?" The parts man, not having this number on the tip of his tongue, says "I'll check my new parts book and find out for you". Since it's the mid '70's by now, his parts book has the Service Part Number rather than the original assembly line number. Joe dutifully writes this down, and on the way home, stops at the local dime store and buys some appropriately sized stencils and some paint. He then goes home, installs the new U-joint and cleans up his drive shaft and re-stencils the part number he got from the Chevrolet dealer onto the driveshaft. In the process, he sees a random number scrawled on the unit as well as some splotches of paint. He knows he didn't put them there, so they must be from the factory and he decides to preserve what is left of them. He re-installs his driveshaft and goes happily on his way, proud of the job he has done.

I am not given to absolutes like some, but if I were a betting man, my money would be on this being the original driveshaft for this car.

Original 67 Driveshaft?

Original 67 Driveshaft?

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