Perches on the axle?
Or hangers on the frame?
Axle perches are different because the 60 axle has a different U-bolt setup. Though I think the width is the same.
The spring hangers are also different. I have a set of 60 hangers and pins that I thought about using, but they are different from 55 stuff. I unintentionally mangled 1 hanger and that was it for me - I ended up making new sets of hangers except for the rearmost ones for the rear axle. The bolts and pins for the 55 spring bushings are 18mm or 11/16" ID. Good luck finding any bolt/pin readily available or cheap that will fit that.
I think you can get a bushing with a thinner shoulder OR you can get a 55 ODed bushing with a 5/8" ID. I decided to go up to a 3/4" bolt because I didn't like the idea of going down in size (however, I think Chevy 1/2 tons use 1/2" hardware for the suspension, if that's an indication of anything). I got the 18mm bushings, put them in the freezer as per some Mud advice, and drilled 'em to 3/4".
I moved the front axle forward a little so I could have a little better approach angle and did a shackle reversal as well. The fixed end of the hangers I made out of 4x4x1/4"(?-might have been 3/16" wall) square tube that I had laying around with one side cut out. I bought some 1/4" thick washers to go on each side of the spring inside the hanger because the spring+bushing shoulder width is less than 3 1/2". Can't have that 1/2" of slop! I outboarded the front to fit a D60 in the future. I'm not sure I'll ever do it, but who knows. Besides, you'll probably be cutting the 60 perches off to turn the axle anyway. It will definitely be a bolt-in affair.

Of course, I realize that by the time I actually get a D60 and put it in I will probably be completely redesigning my frontend somehow anyway.
I'll post some cruddy pics in the next couple of days. Anybody know a good freeware picture resizer?
-Tyler