C2 rear end case cover part number

**Wayne M.** · March 28, 2003, 10:30 PM

Re: C2 rear end case cover part number

Larry -- you want an undated 3871375 rear carrier cover. The "303" was used on C2s up to sometime in '65 (my # 014xx has one, but with the "375" type filler plug threads), and my # 235xx has the "375".

**Larry S.** · March 28, 2003, 11:51 PM

Re: C2 rear end case cover part number

Wayne do you know when the cut off date was on the covers My car with a build date of oct 65 seems to be an earley car.I am missing what your saying with your vin hear are your cars 65'S or 66'S

Thank you for the input.And Your comments have at least confirmed to me that there was a earley case cover and then a later style

**Craig S.** · March 29, 2003, 01:03 PM

Re: C2 rear end case cover part number

My 67 (May 11 build) has an undated 1375 cover, unfortunatly one ear was cracked and I now have a 68 date cover to replace. I don't think they judge the casting dates or casting numbers on the rear end, but, who knows later on, and I am always trying to replace with correct parts...Craig

**Wayne M.** · March 29, 2003, 01:47 PM

Re: C2 rear end case cover part number

Larry -- My cars are both 1965's. The early 4:11 differential is coded / dated AP 9 17 64, on car 014xx, (trim tag D6 -- Nov 6, 1964) and this one has the hybrid "303" cover with the coarse-thread plug. I wish I knew when the cut-off date was -- I suspect it was soon after my unit, and that most '65s had the "375" cover. BTW, the '65 Tech Manual makes no reference to a "303" cover on an early '65, so I'd like confirmation by others.

Your early '66 should have the "375" un-dated cover for sure.

Craig is correct in that the cover # and dates on the CARRIER (not the cover) are not (yet) judged.

**Larry S.** · March 29, 2003, 05:00 PM

Re: C2 rear end case cover part number

Thank You! for your input.Althought not judged I want it to be factory correct.I am removing a 411 read end to go to a smaller set 336 and want this to be the last time I have the rear suspention portion of the car out untill I do the next restoration with my grandchildren in 40 years or so.So I am trying to correct the rear case cover with the correct one even if it means I have to delay the installation of the rear untill I aquire the correct rear cover.
Does anybody reconise what the cover I have on now is for?

**Joe L.** · March 29, 2003, 05:24 PM

Re: C2 rear end case cover part number

Larry-----

The cover that you presently have installed, GM casting #464910, which is known as GM PART #464909, is the 1978-1979 PRODUCTION cover. It is also used for 1963-77 SERVICE and has been the only cover available from GM to SERVICE all 63-79 applications for over 20 years. This cover is drilled and tapped for 7/16-14 spring retainer plate bolts. Originally, this was done to accomodate the 2-1/2" wide springs used for 78-79. When this cover is used with an original 2-1/4" wide spring, used for all 63-77 Corvettes, special spacers must also be used. If your car is equipped with this cover and an original 2-1/4" wide spring, then you should find the spacers, front and rear, between the spring and the retainer bolts.

The original covers were drilled and tapped for 9/16-12 spring retainer bolts and no spacers were used. If you convert to the earlier style cover, you will need to change the bolts to the 9/16-12 size. Originally, these were a special bolt with a longer-than-standard unthreaded shank. Those bolts have been discontinued for years, but standard configuration bolts can be used.

Also, the spring retainer plate used with the 464910 cover and 7/16" bolts has smaller bolt holes in it than the cover used with the 9/16" bolt hole configuration. Otherwise, the plates are the same. You can enlarge the holes on your plate, if necessary, to accomodate the 9/16-12 bolts. The GM spring retainer plate for the 9/16" bolt holes is discontinued.

**Craig S.** · March 29, 2003, 05:35 PM

Re: C2 rear end case cover part number

Wayne - so is the 1375 judged on the cover? How about the date on the flange near the oil fill plug? I suppose I could look for one that has no date like my original 67...thx!...Craig

**Larry S.** · March 29, 2003, 09:14 PM

Re: C2 rear end case cover part number

Thamks Joe and all else for there input

Joe I have no spacers I had removed a trw fiberglass spring and replaced it with a reproduction metal spring I remember the metal one not fitting correct,I also had ordered reproduction bolts for when I installed my new correct spring,And the bolts would not fit they were too thick.I just figured the supplier sent me the wrong bolts.(I still have them)

What is the correct rear case cover I shold be shopping for 135 or the 303?

Thanks again every one

**Joe L.** · March 29, 2003, 11:45 PM

Re: C2 rear end case cover part number

Larry-----

GM casting #3871375 is the one you need. It's, by far, the most common one, too. It was used from 1965 through 1977. So, there are lots of them out there.

**Wayne M.** · March 30, 2003, 09:36 AM

Re: C2 rear end case cover part number

Sorry my response was fuzzy; but so is the description in the '65 Tech Manual -- you have to read it several times to figure out if they're talking about #s and dates on the cover or on the carrier.

#s and dates are not judged, probably based on difficulty of seeing them with the spare tire carrier, muffler and wheel blocking the view. And yes, I'd look around for an un-dated "375".

**Craig S.** · March 30, 2003, 09:45 PM

Re: C2 rear end case cover part number

Thx Wayne, there must be a few out there. I thought maybe my 67 just missed the cast date on the cover, but now I have learned something new...and will look for the right undated 375....thx!...Craig

**Larry S.** · March 31, 2003, 07:24 PM

Re: C2 rear end case cover part number

A sincere THANK YOU AGAIN to all who helped.I have allready found a new rear case cover (undated)and it will be shipped on Wensday.

The wonders of the internet what did folks do prior to find information like this

C2 rear end case cover part number

C2 rear end case cover part number

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment