Got a 2001 Blazer and I owned one before but never got into some of the things. What rear end is common in these things in case I want to put a locker in it?

I'm not going to put a big lift and bit tires but putting a locker in the back is on the list.

 

Look under the back of the Blazer. The center of the rear end will have one of two things:

At the bottom of the housing, a 7.5" has curved 'fangs' on either side. An 8.5 rear end will have triangles (one side of the triangle flat to the ground, the other straight up and down).

Also, an 8.5 has axle tubes that get wider at the center section, kinda flares larger before they connect to the center.

 

There are articles on here that tell you how to look all that information up by using the RPO codes found in your glove box.

 

The RPO codes will tell you what gears you have, but it won't specifically identify which size rear axle you have. If it's a ZR2 then it's definitely a 8.5 or 8.6" rear end, but if it's a non-ZR2 it is likely a 7.5", but may actually be an 8.5". It depended on which factory it was assembled at, and what options were originally ordered.

 

You don't want to go the the effort to actually install a Gov Bomb which throws a cog and locks when one wheel spins too fast. A Detroit Locker is overkill. You want an Eaton Posi with discs if you're going to go to the trouble. Be careful as bearing sizes and axle splines change from rear to rear in the late nineties. You need to know exactly what you have and what you want to go to.

7.625 has 28 spline axles
8.6 has 30 spline axles and bigger carrier bearings than the 8.5

Your vehicle is too new to have an actual 7.5 or 8.5, but stuff from them can still fit except for carrier bearings on the 8.5/8.6. However they make bearings that adapt carriers from one to another.

Easiest giveaway for the 8.5/8.6 is that the axle tubes for a S10/Blazer go down in size as they go out from the center. See here.

 

Diff Wizard