[cv70chall]

I'm going to come right out and admit I'm ignorant when it comes to the rear end, gears and such here.
I will have the freshly rebuilt and slightly bumped 360 in the engine bay this weekend along with the 7272 transmission.
The original motor was a 318 and I would like to know what gears would be in the Spicer rear end I have. (In a perfect world, I would have a nice 8 3/4 Dana Posi Rear End, but I'm not Donald Trump and this ain't a perfect world.)

[Eddie]

Probably a 3.23 open diff. it's very easy to test, just lift the rearend up, turn one wheel, the other should move in the same direction, if the other wheel turns the opposite way it's an open diff. I would just run what you have with your mild combo. Chrysler used limited slip/sure grip now called anti-spin,,posi is a gm term. You can also turn the drive shaft 1 revolution and count how many times the wheel rotates,,this will give the ratio if your centersection doesnt have the tag describing the ratio but probably 80% had the 3.23 8.75 diff in 318 cars. This is what mine was with 318 2 barrel carb. Does this answer yor question? There is a way to find out how healthy the CS is but it involves removing the CS and placing it in a fixture,(easily made by using angle iron,,then placing the ring gear under load by shoving a large screwdriver against the ring gear and rotating it by turning the yoke, then observing the wear pattern on the ring gear(after cleaning the ring gear and using lipstick or the yellow paste they give you in the re-build kits. If it's too high or too low a pattern then either the pinion or carrier bearings or the races are worn and should be corrected to the correct pattern....but as I say this is a lot of work. I would just drain the old lube and re-fill it with quality fluid and run the piss outta it! BTW, it might be a cone style sure-grip which is Auburn, clutch style which is Spicer, or open carrier which is the Chrysler made unit. I am pretty sure Chrysler used outsourced limited slip units as described above. I would definitely use new U-Joints on the driveshaft and new yoke straps,, they are very small bolts 1/4- 24 I think.(DONT over torque them) they will snap right off.(170 inch pounds) or around 13 FT. lbs.

[burdar]

Since you said "Spicer" rear, I'll assume you have an 8 1/4" rear instead of the 8 3/4" right? Is there a cover on the back of the housing that can be unbolted? If you have the 8 1/4" rear(with a cover) you can removed the cover and look for the ratio stamped on the ring gear. You'll probably want to replace the fluid and the cover gasket anyway.

I don't know what ratio's were available in the 8 1/4" rear. I know in 73 my 8 3/4" rear has 2.76 gears. That was the standard ratio for a 318 car. The only other optional rear gear was a 3.23 sure-grip for the 318.(in 73) I'm going to run a 3.23 in my car. That's what I'd run in yours too. A 3.55 would give you some more torque off the line but will cost you some MPG on the highway.

If you do have the smaller rear end, I'd just save up for an 8 3/4 swap down the road. It's going to cost you a good chunk of change to swap gears in the 8 1/4. My $.02

Here's an axle ID chart so you can figure out what rear you have now.
http://www.moparts.org/Tech/Archive/axle/6.html