Ok but will the axle fit without my rear tires stick out more than front?

 

The axles are different widths, depending on if it's 2wd, 4wd, or ZR2. The 4wd axle is between 2-3" wider than the 2wd axle. So if the donor Bravada is a 4wd then it will push your rear tires about 1.5" wider on each side. That's a total of 3" wider. If the donor Bravada is 2wd then it will match yours fine.

The main reason to reprogram your PCM after a gear swap is so that your speedometer will be accurate. I believe that it will affect shift points too. It seemed to change the way my Blazer shifted when I reprogrammed the PCM after changing gears.

 

I don't think you will have to reprogram the computer, but the speedometer and shift points will be off slightly. I have a buddy who put 35" tires on his JK wrangler. It threw off both his shift points and transmission. Not to the point of not being able to drive it, but it was annoying. Going from a 3.42 to a 3.73 isn't all that extreme, though, so I probably wouldn't worry about it. Just know that you will be going a little slower than what your speedometer says after the change.

 

Do the 2wd bravada's have 3.73 in it?

 

so your saying the zr2's axle would push my rear tires out as much as a 4x4 bravada?
will the zr2's or 4x4's rear axle fit without any problems?

 

The ZR2 axle is almost 4" WIDER than the standard 4x4 axle. The standard 4x4 axle is 3" wider than the 2wd axle. so the ZR2 axle is almost 7" wider than the 2wd axle. I really do not think you want a ZR2 axle.

Either a 4x4 axle or a ZR2 axle will technically fit, in that they will bolt up fine. The problem will be that they are both wider than your factory 2wd axle, and will push your tires out farther. A Bravada axle is exactly the same as a regular Blazer axle. A 4x4 Bravada axle will put your tires wider about 1.5" on each side (3 inches total).

I believe that the Bravada's came with 3.73 gears, but you need to check the RPO codes in the glove box of the donor vehicle. If it says GT4 then it has 3.73 gears. If you want the locking diff you need to also look for the RPO G80.