I am in the midst of a rebuild on a 95 Formula rear. I am putting in a Detroit Truetrac carrier and Motive 4.10 gears. The height from the base of the pinions to the top is the same. When I compare the width of the pinion "head" the 4.10 is about 2/3 the size of the stock one. Is this normal? I suppose that is why the 4.10 is a lower gear compared to the 2.73 that it came with, right? That must be why it is a weak point in the 10 bolt? I will post comparison pictures tonight.

 

Yes its normal for the pinion gear to be smaller. The higher the gear numerically the smaller the pinion gear.