My spring over axle conversion was quite simple, due to the fact that I did not cut down my axles, meaning I left them full size. The rear axle that I am using is a Dana 60-2 Semi-Floater 5 on 5 1/2 lug, it is out of a 1973 Jeep J-10 1/2 ton truck with the Heavy Duty option. For the front I am using a 1978 Jeep Wagoneer Dana 44. I chose to go with this D44 instead of the 1973 front D44 that I got out of that same J-10, because the 73 was a closed knuckle, drum brakes, and had axle shafts the size of a D30. YUCK! So the 78 won out due to disk brakes and bigger shafts, but it was 6 lug. You can see my write up on the change from 6 lug to 5 lug here.

For the rear axle I positioned it under the jeep, with it jacked up and springs attached, measured out from the backing plates to the springs to center it. Then placed the spring perch on, and bolted it up. Noticed I said placed, I have not welded those perches down yet, due to the fact that you want the weight of the vehicle on it and driveline in. I only have the driveline in so far, no body mounted up yet. You want the weight so you can set the angle of the driveshaft. For the correct angle, both yokes, transfer case and axle, should be parallel. Meaning the same angle on both. And this is with a 2 joint drive shaft. With a CV shaft, and it being bolted to the transfer case, the axle yoke should be 2 degrees different. This will allow for proper bearing spin inside the u-joint. Keeping them lubricated.

For the front axle, it was mostly the same. Except I cut off the old spring perches due to they were below the axle. I also had to grind extensively into the differential housing on the passenger side to get my perch on there correctly. Also since I did this I had to raise the drivers perch by just over 1/2", and I did this by welding some steel on top of the perch I had, don't forget to drill the hole for the spring bolt. You must also keep in mind the caster angle. What that is, is the angle of the knuckle, from upper to lower ball joints. Ideally you want 6 degrees positive caster. Meaning the top ball joint will be tilted towards the rear of the vehicle 6 degrees. It's not hard to do, just get yourself a protractor of some sort, and you want to make some sort of line between the upper and lower ball joints (the middle of them). And find that angle with the weight of the vehicle also. You want the spring perches to be level, then turn back the axle towards the rear while using your angle finder, and just go to 6 degrees. You do not have to have exactly 6, but you must have positive caster of some sort, or your vehicle will be practically undriveable, 6 is just ideal.

NOTE - When setting your caster angle, keep in mind your drive shaft angles. You should be able to find a compromise between both of them where it will all work together. You just don't want to set the caster angle, then look to find your pinion pointing into the ground.