Rear End Question

[Martin64]

Is there a way to tell what the gearing of a rear end is just by looking at the outside of it?

Here's the situation, one of my neighbors moved out and left a rear end in the car port. Management had it moved over to the dumpster, which just happens to be next to my garage, and low and behold it has 6 lugs and drum brakes. After closer inspection it has a "GM" casting on it in raised letters. So right away I figure it's a 6 lug GM rear end that, with just a little luck, may be the 3:08 that I'm looking for.

I've moved the rear end into my garage so I can figure it out.

There's also another way to tell but I forgot how. Something about turning the axle and counting the turns at the yoke and multiplying by some number.

[kaycee]

You might as well as pull the cover off and see what is stamped on the ring gear and devide them and that will give u your ratio.This is the only for sure way to tell allso u will see if it is full of metal shavings or not.Good find look and see if it has coil spring or leaf spring perches.

[lukecp]

There should be a ratio stamped on the ring gear, should say something like
"GM 41 10 4-72", with the 41 being the teeth on the ring gear, and the 10 being teeth on the pinion, working out to 41/10=4.10 ratio. Should also have a date code, 4-72 being April '72. I've been inside two 12-bolts and they both have this. Just spin the ring gear looking for the stampings, and if they aren't there count the teeth as menitoned above. Also check out the conditon of the gears as long as you are in there.

[69 Short Fleet]

I'd pull the cover as mentioned to see whats in there, prolly a good idea to check the internals condition anyway.

[68w/sbc406]

with some luck, you could figure out that he was saving it cause it was a posi unit

[Martin64]

Ok, it is a 4:10 and I'm not positive but it may be a posi. It has some extra looking hardware inside that I haven't seen before. If anyone wants this rear end, come and get it. If you're feeling gratuitus and want to swap me a 6 lug 3.08 rear end then I will gladly accept it. Otherwise it's yours for the taking. I got it for free and will gladly pass it along

The teeth on the ring gear looked alright. I did find a couple very small pieces of metal, about the size of #2 pencil lead that breaks off a pencil end when you press too hard while writing. Since it still has oil in it I just rolled it so I could get the cover off to count the ring gear. The rear end cover has been welded up. It looks like it may have came off a 4WD. It has leaf spring mounts on it.

Again If you want this rear end it is free for the taking. I'm picking up my new Harley-Davidson today and the rear end is taking up too much room in my garage.

[68w/sbc406]

if you spin the part of the rear end that hooks to the drive line, how do the tires spin

[Martin64]

I don't know. It doen't have brake hubs to see spinning and I couldn't see both axles at the same time and didn't have an assistant around to help me with that part. But I put it back outside...had to make room for my new Harley I picked up today.