Hey guys, I have a 99 bravada I wonna swap out the front diff & do the posi lock mod to have control on my 4wd. I'm having a hard time to fin a front diff for a blazer with 3.73 gears. So A) where should I look? Any tips or advice? B) should I just get a blazer 3.42 & rebuild it w/ 3.73 gears & if so where can I finds a kit to include everything? Also would I need any special tools to rebuild one?
Thanks Mike

 

If you can find one from a ZR2 I'm pretty sure they all came with 3.73 gears. Do you have any Pick-n-Pull type wreckers near you where you can go pull parts yourself? That's been the best place to find parts for me. That and people parting out trucks on Kijiji or Craigslist.

I've never replaced the gears in a diff, but I've heard it's not exacly simple. You might be better off just having a shop do it for you if you decide to just put in new guts.

Good luck!

 

If you haven't ever set up gears or have somebody good to do it have it done at a shop. A few thousandths off on setup can have the gears exiting the case.

 

Well I found a junkyard about any hour from my house. That says theyhave a s10 with 3.73 gears & it's a GT4 rpo code which matches what I could find on google. Is there a way to varifiy what the gear ratio is in the diff once it's out in the vehicle?

 

without splitting it open and reading the numbers no way to be 100% sure. You can try to turn the yolk 3.73 (about 3 3/4 turns) and the axle should turn once if I remember right. That way is real iffy and if your off by just a bit a 3.42 can fool you.

 

Well I guess if the t case blows up ill know.. Lol

 

Unless money is tight I'd be tempted to split it open to check gears, replace the seals, and change lube in a junkyard part. As long as you don't remove the gears replacing most all the seals is a easy diy job on the work bench.

 

I just wonna make sure 100%. So your saying its ok for me to split the house by pulling the case bolts & I can take it apart with out the guts puking out on me?

 

Front Diff Rebuild Intructions Needed - S-10 Forum

That might help a bit, if it don't search gm 7.5 ifs diff rebuild. Its not really that hard for me but I was raised as a mechanic and don't know your wrenching skills.

 

If its a standard differential and positrac carrier it wasnt difficult for me to take one apart change the gears and put it back together.You are going to need air,impact gun and 3/4`s heavy duty socket though for the bolts on the ring gear.Check and make sure the pin going through the carrier to the gear isnt excessively wobbly.I know that I have ran into that problem on alot of GM 10 bolts.You can take and count each teeth on the ring and pinion gear and you have to do some math to figure out the gear ratio.