Rear Axle 4.2 gear ratio
 

Hi, I'm new to the site. I have a 53 GMC 1/2 ton truck that I'm upgrading the suspension. I'm looking at a rear end online that has 4.2 gear ratio, that came out of a 2002 4x4 LT. Can anyone tell me if that is 8.5 ring gear and what is the drum to drum dimension is?

It is most likely a 7.6" ring gear, not an 8.5"
I'm not sure what the width measurement would be from hub to hub (disk brakes, not drums), but if a full-size truck axle will work for you, you can get them practically anywhere for almost free.

I need the WMS to WMS to be 60 inches, that's why I'm looking at the 4x4 (without ZR2). I wanted a stronger 8.5 ring gear, preferably a 3.42 gear ratio. I've been searching every where, can't find one. When I posted on other FB groups, most of the responses were from scammers.

I have the one out of my Blazer that I would happily give you for free, but I'm in California, and you're probably in Canada or something, lol.

Unfortunately, it's 200 miles away from me right now, so I can't measure it for you.

I'm in Texas. If it came out of a 4x4 without the ZR2, it's 60 inches. The 2WD is about 4 inches shorter. Does it have the 8.5 ring gear? Also, I have family in Redwood City that can ship it for me.

It is out of a 4x4, but it isn't an 8.5 ring gear. I may be wrong, but I think a non-ZR2 8.5 rear is pretty rare.

That's right, they are rare. I'm considering getting a ZR2 and having it shorten to 60 inches. There is a shop here that does custom work on rear ends, but they're pricy.

If you're going to have one shortened, start with a full-size instead of a ZR2. They're a dime a dozen.

Yeah your right, might even be able to find a 12 bolt.

A 12-bolt is only marginally stronger than a 10-bolt, and it's going to cost quite a bit more. You would be better off with a 14-bolt semi-floater. Coincidentally, I also have one of those I need to get rid of, but it has 4.88 gears, a Detroit Locker, and aftermarket axle shafts, so it probably wouldn't work very well for you.