rear end size?

[jomama]

hey guys hows it goin? i was wondering what size rearend i have 7.5,7.625 or 8.5. reason is is im changing the oil and i have to buy a gasket and there are options and also i want to put synthetic back in and all i can find is mobil 75w-90 is that ok(its an open diff.)? well thanks in advanced.

[Sparky2263]

Y02 : Ring Gear, 7.50 In., Dana, (s.p.o.)
Y03 : Ring Gear, 7.62 In., Saginaw, (s.p.o.)
Y04 : Ring Gear, 8.50 In., Saginaw, (s.p.o.)
Y05 : Ring Gear, 8.50 In., Dana (s P 0.)

[jomama]

Y02?
Y03?
Y04?
Y05?
thanks sparky but where do you find these spo codes thanks

[Sparky2263]

I think an 01 the list is in the glove box. Sticker with a bunch of codes on it.

[jomama]

well i looked at that but i didnt see anything that looked even close to any of them.

[Sparky2263]

Hmmm, pulled those codes from an rpo code list.

I can tell ya' how I know what I've got, the 7.5/7.625 axle tubes stay the same diameter as they reach the diff housing. The 8.5 axle tubes step up in diameter as they reach the diff. housing.

Ya' know, just noticed those codes are spo (special production option) rather than rpo (regular production option).

Wonder where our rpo code experts are?

[XxInFaxX]

this is a list of all the RPO codes that you will find in your glove box. its a long list but it will help you understand what you have.



http://www.sicgmtrucks.com/forum/showthread.php?t=702&highlight=

[Sparky2263]

That's where I got those codes. Didn't notice any other diff codes but they could be labled something like "HD suspension" or something like that. Kinda' like the "Camper Special" on my old T-10.