Differential Case Part #'s

[Gregory G.]

The part numbers 0J357W7E1 are located on the cases bottom forward of the cover.The cover date code,top right is E149.
What is the gear ratio,and is this a service or production part?

Greg

[Joe L.]

Re: Differential Case Part #'s

Greg-----

I believe that it's a PRODUCTION unit. However, I think that PRODUCTION and SERVICE assemblies were coded the same, so there is no way to know, for sure. The "OJ" code indicates a 3.70:1 ratio used from 1978 through 1979, although there's no guarantee that those gears are in the case now. The remainder of the coding would indicate a unit manufcatured during the 1979 model year.

[Gregory G.]

Re: Differential Case Part #'s

Joe,

The front cover date code E149.You are saying its a '79 not '69 due to the Case part#.The E stands for Eaton,but the W stands for Warren?Could it have a '69 cover?

Greg

[Joe L.]

Re: Differential Case Part #'s

Greg-----

All 63-79 Corvette differential units were manufactured at Warren, MI and all except 63-64 used an Eaton posi unit. So, that information doen't mean very much. The "OJ" code was only used for 1978-79. So, it has to be one of those years.

[Gregory G.]

Re: Differential Case Part #'s

Joe,

Does a 78-79 cover spring bolt pattern align with a 69-70 spring bolt patten?My 9 leaf factory original spring fits properly to the rear differential cover,so the E149 cover casting date may then be a 69 not a 79,which then means differential covers are interchangeable for those years,but the OJ stamping as you stated is 78-79.Do you agree?

Greg

[Joe L.]

Re: Differential Case Part #'s

Greg-----

The 78-79 cover will fit perfectly to a 63-77 Corvette application. In fact, the 78-79 cover became the GM SERVICE cover for all 63-79 applications after the earlier style was discontinued. The 78-79 cover is easily identified, too. For one thing, it carries the casting number "464910". For another thing, the 4 spring bolt holes are 7/16-14 thread size. The 63-77 covers were originally 9/16-12 thread size. The change in bolt size was for the purpose of accomodating the 2-1/2" wide spring used for some 1978-79 Corvettes. When the 78-79 cover is used on an application with a 2-1/4" wide spring, such as any 63-77 application, special spacers have to be used to "take up the slack" between the bolts