well i brought some gears from a guy local, and he said they are 4.10 and fit a 7.5 rear, well my mechanic has dicked around for days and said the bolt pattern dosent fit my rear end, is the bolt pattern for a 8.8 and 7.5 different and how can i tell if the ring and pinion i brought are actually a 7.5 ? i honestly dont trust any of the two people i mentioned so can any one help me greatly appreicated .
The 7.5 and 8.8 axles are both 10 bolts. However, the axles are different size - 1.3" difference so the rear covers won't interchange. I find it interesting why you would try running 7.5 gears in an 8.8 axle. The spline count has to be the same if you wish to use the original axle shafts. Anyway, check here Yukon Gear & Axle and these guys will be able to point you in the right direction. I've added on some photos just for reference, but to know if the gears are interchangeable between the different axles, you'll have to ask the guys at Yukon Gear.