Your 55 2nd came with optional three speed overdrive, though they are rare. This option included a 4.10 rear instead of the 3.90. This should be a bolt in. I have run them, they allow you to cruise a 70 but are tough to find in good shape and parts are getting scarce. Instead I now use a T-5. Holds up fine behind my 6 so far. I have a article in the Tech section, no need for an adapter plate for early models of the T-5.
As far as brakes, I use the Kevlar shoes from Dyno Praise and have never noticed any fade. I have 35K on them now and they are still in good shape. I also like to run radial tires and a aftermarket sway bar. The truck stops and handles well, though I feel I am at a disadvantage compared to most vehicles, and I try to keep that in mind when driving.
