I have a 97 blazer 4 door with 3:42s I'm gonna be running 31" tires here soon and was wondering how hard it is to switch gears in a front its diff. Now I know none of u know me or my skill level so I will add this. The rear diff is not a problem I know all about the preload and gear tooth pattern and backlash. My main concern is taking out the front its and cracking it open. Plus if I'm towing should I go with 4:10 or 3:73. Also how do I tell what size diff I need gears for. I see gm has a 7.25 a 7.6 8.5 there's all different sizes. Thanks for any input or insight u guys might have

 

The front isn't any harder that the rear for setting up gears, just more labour intensive. Personally I would go with 4.10 gears, but I prefer a bit more performance over fuel mileage. 3.73 would keep you near stock gearing. Front is 7.2, rear is 7.6 most likely.

 

Cool tanks for the input. No blazer came stock with 4:10s did they? I probably can't got to a ez pull and get the whole diff that would seem a lot easier

 

I think some did get 4.10s. Look for rpo code "GT5" in the list in the glove box.

 

I have yet to see a Blazer with 4.10s... Maybe an option in the trucks?

 

I've done quite a bit of research online about this and as far as I can find, while there were some S10's that came with 4.10 gears it was only the 2wd 4 cylindar engines that came with those gears. Almost all the rest all came with 3.42 or 3.73 gears. I have heard of some of the 1st gen Blazers with 3.08 gears too.

Personally if you're wanting different gears to go with your 31" tires I'd suggest just finding a Blazer with 3.73 gears and swap the whole rear axle and front diff. You can get them from a Pick-n-Pull type place for way cheaper than you can get the gears replaced in your current differentials. I did my own on the driveway with normal hand tools. You do need to make sure that you get diffs from the same series as yours. Since you have a 97 you should look for a 95-97 truck unless you're getting new CV axles too. If you get diffs from a newer truck you'll have to replace the front CV axles as well with the newer style because the older and newer styles are not compatible.

 

OK thanks for the info