I'm 95% sure you don't have 3.55 gears in a 55 2 ton, more like 6.7 something or at best 5.14 I'll guess.
To check for sure you can jack up the rear, count turns and do the math.
Transfer case ratio leave blank or 1, you don't have one. Transmission ratio is whatever it is in high gear in this case, either 1 for direct drive (original transmission) or very likely 0.73 for an Over Drive that comes behind a Cummins.
Correct, 55 model and later big bolts with the 10 lug pattern on 7.25" bolt circle should have a 5.25" center hole, this is a change from the earlier 4.75" center hole.
Grigg
