Yet Another Small Axle Vs. Large Axle Thread
 

So my friend picked up a new third member. Its an LSD differential, and 3.909 ring and pinion. The seller CLAIMS it came out of an 83. We were just wondering it there is any easy way to identify what year the differential is from thus whether it is small or large bearing. I'm assuming since its not the 4.10 its not a GSLSE 3rd member, but who knows at this point, we all know how craigslist goes, especially when the seller doesn't know what he has and lets it go for $20 =D

His car is a 83 GS of course with the small bearing rear end.

Count the splines

Easy enough, any idea off the top of your head what the numbers are for each before im off to search?

24 Spline for small axle, 26 for big. There was an old thread that I believe has been archived, where some of the old veterans were discussing all the differences and measurement comparisons of the different rearends. Some useful info in it, including flange differences for driveshafts thru the years

I knew the driveshaft stuff, which was no help as some 83's used the same one as the big bearing cars lol.

I actually found that exact thread right as you posted that funny enough. Good ol search.

I hear ya abt the driveshaft thing being kinda useless. I had my hopes up back in the day when I got a GSL rearend, that had the later large flange. Didn't know if I had the big/small rear until I replaced the axle seals, and discovered I had the small axles :(

ALL '83 used the "square" driveshaft bolt pattern same as the big-bearing axles. There's no "some" about it.

The EASIEST wat to check is to just look at the housing ends. There are three exposed nuts for the bearing retainer. On a big axle rear, the two that are parallel to the brake caliper are on the same side as the brake. On a small axle rear, the two are on the opposite side of the brake caliper.

Super simple and you don't need any tools at all!

Note: This is of zero use if you're looking at a drum rear...

if you're a nerd you can look on the ring gear for a stamping, it'll have a 4 digit number, like m020 or something, and then you can look up the ring and pinion in the parts fische.

non nerds can count the teeth on the ring gear and on the pinion, and divide to get the ratio.

the OP only has the 3rd memeber, no axle housing.

Call me a non-nerd then i guess lol.

And yeah, no axle, just the pumpkin, ring, pinion, and LSD, all asembled