Grigg,
I have a Dana 80 out of a 1995 Chevy with 10 lug hubs and rotors and a Dana 70HD out of a 1994 Oshkosh Stepvan with 6 lug budd hubs. I thought i had it made, swapping the 70HD hubs onto the 80 axle, no moving spring perches, right gear ratio, etc. The 80 was a 37 spline axle, 70hd was a 35 spline axle. Side gears I believe are interchangeable between carriers.
Differences.
1. On the Dana 80, the spindle is a different diameter for the outer wheel bearing race, larger on the dana 80, smaller on the Dana 70HD. Not a deal breaker as I suspect the outer wheel bearings from the 80 could be used in the 70HD hubs.
2. On the spindle for the Dana 70HD, the distance from the caliper bracket mounting flange to the inner wheel bearing is 1/4 inch more on the Dana 70HD than it is on the Dana 80. Inner wheel bearings are the same. The offset off the rotor hat to the hub puts the 70HD rotor hitting the caliper mounting bracket (both Dana 70 and the original 80 caliper brackets tried) when used on the Dana 80 axle, not by much but the 1/4 inch is needed to space out the Dana 70HD hub / rotor. My fix would be to make a 1/4" spacer to space out the inner wheel bearing. Problem is you have to space out the sealing surface 1/4" as well so the seal has a place to ride but when you space it out, the seal rides at the joint from the original housing and the spacer.
Long story short, called several people knowledgeable on axles and they all said no easy way to put 70HD hubs on a Dana 80.
By the way, thanks again for the axle swap article. My front axle is in process as I write, already cut and soon to be rewelded. The rear I am waiting on spring perches and hub studs / gaskets to reassemble and install it. Hydroboost is sitting on the garage floor, only waiting on finding a steering box. The cabover is proving to be a little problem since the box needs to ride on the top of the frame I think, not the outside. I have a topkick steering box from a mid 80's truck that I will be picking up in 2 weeks that hopefully will work but if not, I will be checking out buses in force to find one that will work.
Ryan
