I sort of doubt that a 1.5 ton would have a 3 speed transmission. The standard would have been a 4 speed. Perhaps they meant a 3 speed with the granny low gear, a lot of folks get this confused. As far as I know the Eaton 2 speed rears (17.5+) were all electric operation and the Chevrolet rears (15K) were all vacuum operated.
I cannot help you on the brake question but am sure others will know.
