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As far as I've seen, they can be found in pretty much any year of 2nd gen S-series trucks, but I don't believe they had a separate RPO code. As well, all ZR2s had the larger 8.5 or 8.6 rear ends, but those axles are also 3 inches wider than a normal 4x4 S-series truck axle.
What year s10 blazer came with this rearend?
thank you
You can find them in second gen Blazers and S10s 7.5, 7.625, 8.5, and 8.625 were all used so you have to know how to ID. The 7.625 and 8.625 rears are disc brakes. 2WD 8.625 rears are found behind V6-5-speeds in the 2000-2004 vehicles. 4WD 8.625 rears are typically found in ZR2s of similar years but can be found in regular Blazers and S10s. There are 3 axle widths. From narrowest to widest - 2WD, 4WD, and ZR2 4WD. All the 8.625 rears have 30 spline axles. These are the ones that you want. You will not find a 3.73. Use a Yukon Eaton-clutch-type posi for an 8.5 and a gearset for 8.5. Mount in the case with carrier bearings for a 12 bolt rear (that and 30 spline axles are the big differences in the 8.5 vs 8.625). I know all this because I installed an 8.625 housing with 3.73 gears in my 2WD S10. Way I ID S10/Blazer 8.5/8.625 rears is looking at the axle tubes going into the center section. The tubes increase in size right before entering the center section on the 8.5/8.625. On 7.5/7.625 the tubes are straight.
So what do you have? 2WD, 4WD, or ZR2?
If you want cheap 3.73 and posi, you might want to consider the Ford Explorer 8.8 swap. Lots of those in the junk yard. But on that for 2WD you have to cut and re-weld one of the tubes and then use two short axles (on original they are different lengths). If used in a 4WD you might get by with just moving the spring perches. Not sure of width of original Ford Explorer 8.8 rear end.
See the hump in the axle tube just to the right of the center section? That is unique to the 8.5/8.625 S10/Blazer rear. Note, I opted to go back to drum brakes on mine - but it was originally a disk brake 8.625 rear.
I have a 01 s10 xtreme v6 5 speed 8.5 rear with 3.08 that I will eventually ls swap with a t56/tr6060 and want to put 3.73 with posi and disc brakes. But if I boost it I’ll do 3.42
Yes, I believe the drum brakes would indicate an 8.5 (I may have got the year split wrong + there may have been a transition year). My 2001 4WD Blazer has a 7.625 with disk brakes on the rear. So I suppose any combo is possible during the transition. But I have heard that only the V6-5speed gets the big ring gear (in 2WD form).
The best way I know of to tell for absolute sure is to look for the hump in the axle tube and then count the splines on the axles. 8.5 have 28 spine axles and 8.625 have 30 spline axles. 7.5 have 26 spline and 7.625 have 28 spline.
Disk brakes should fit fine on an 8.5 that has drum brakes if that is what you have (since I have drums on a disk brake rear). The only difference in aftermarket parts when building an 8.625 are the carrier bearings and shims for the carrier bearings along with a larger ID pinion oil seal. Aftermarket Ring/pinion, pinion bearings, and aftermarket posi carrier are the same. This I know for fact as I did mine myself. Hope this helps and doesn't confuse.
Yes, I believe the drum brakes would indicate an 8.5 (I may have got the year split wrong + there may have been a transition year). My 2001 4WD Blazer has a 7.625 with disk brakes on the rear. So I suppose any combo is possible during the transition. But I have heard that only the V6-5speed gets the big ring gear (in 2WD form).
The best way I know of to tell for absolute sure is to look for the hump in the axle tube and then count the splines on the axles. 8.5 have 28 spine axles and 8.625 have 30 spline axles. 7.5 have 26 spline and 7.625 have 28 spline.
Disk brakes should fit fine on an 8.5 that has drum brakes if that is what you have (since I have drums on a disk brake rear). The only difference in aftermarket parts when building an 8.625 are the carrier bearings and shims for the carrier bearings along with a larger ID pinion oil seal. Aftermarket Ring/pinion, pinion bearings, and aftermarket posi carrier are the same. This I know for fact as I did mine myself. Hope this helps and doesn't confuse.
so if I’m not confused
I can grab the backing plates with the brake shoes from any 2wd Blazer and replace my drum backing plates with them
Didn't you mean can you replace drums with any rear disks from later Blazers? I believe that is correct, but not sure how factory abs will work or if front/rear pressures will be right.
11-03-2023, 10:50 AM
