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So I recently picked up a front and rear axle from a 82 GMC c70 and was trying to identify the rear end(found out it's a Eaton 17221 2 speed with a 6.57 high and 8.96 low) so I know the ratios and can see if I can get parts/gaskets and if anyone knows of a solid source that would be great.

So my main question is- Is the differential limited slip I was looking at this parts list I found online and it shows that it has clutch packs in it which the only thing I can think of would be for limited slip so I am just wondering what that implies if I take it apart to inspect before I install it.

Here is the link I found https://www.wholesalegmpartsonline.com/showassembly.aspx?ukey_assembly=430720

Are those ratios high enough for your 327, I presume you have some kind of OD in it?

Ed

No OD it's just got a standard sm465 but I calculated it out with 40in tires I can do 70 at 3000rpm in 4th gear high

When you pull the diff cover for inspection, you should be able to see inside of the differential, if you see clutch discs on the axle shaft side within the differential then it's a limited slip/posi/locking unit. If you see only gears then it's an open differential.

I'm not sure what calculator you used, but I question your figures. Through the years I drove my Fire Engine over 30K miles on many 1000+ mile trips. With the stock 200 hp V8 and and a curb weight of 14,400#, with 6.14 gears, 40" tires (11.00-22.5 tires) and a direct drive trans I ran 65/66 mph at about 3500 rpm. Per the Spicer Calculator and your info it looks like you'll run about 54 mph at 3000 rpm. If you're bumping the governor at 4k rpm you'll be running at about 72 mph (faster that the truck was designed to go).

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

Mike B

I just used a regulator calculator like I normally do and it has always worked for me. I am running un-governed I think this motor was rebuilt and there is not governor unit on the carb even though it is a model of carb that would have come with the truck

Do you know if I can get gaskets for it or could I cut them out and if I cut them out what gasket material should I use

I would think you should be able to get seals and gaskets for that axle, it's not ancient and Eaton is still a major supplier for trucks.

So I found a service manual for the axle after some digging online and apparently you are just supposed to use silicon gasket maker on it at least where the 3rd member bolts on I am gonna do some more reading into it and I also found a Eaton no-spin application guide and my axle is included so if it doesn't have LSD I might see about installing it because I know it would be useful