I got a '78 Bronco rear end that is 65" flange to flange. There is about 2-3" of the axles sticking out of the housing. If I were to convert to disc brakes could I get axles that sit further into the housing effectively narrowing the rear end?

 

No, axles hang out a certain amount to allow for the brakes. GM used 2 3/4 inches and most of the 9 inch Fords used 2 1/2 inches. The brakes are made to work with this amount of hang out. The axle bearings and the radius on the back of the axle flange also need room. You can not alter the amount of hang out on the axles to change the rear end width.

 

Thanks.