According to the manual, the '55-'59 (bendix brakes) use the slide on style drums, too, same as the Huck. Probably a change in the early '60s. I've got a '60 manual, not handy at the moment, but I'll check it to see what it says.
Also, according to the info I have, there was no factory 3.90, however, there is a listing for a 3.54 for '72. I have actually seen 1, but i beleive that they're extremely rare.
Also, the HO72 generally had 5.13 gears, usually found only in 1 tons.
