1/2 tons didn't have 19.5 wheels.
1 tons and 3/4 tons share the same bolt pattern, wheels, parts, etc (1/2 ton is six lug instead of eight).
19.5's are the tubeless equivalent for the 17" tube type, BTW.
Some of my crap:
1963 C-30 flatbed dually 292/SM420
1965 C-10 LWB fleet 250/column shift 3 speed
1965 C-30 9' stepside 250/SM420/4.10 gears (my DD)
Website I made for my crap:
http://www.66submarine.com 
