I've only seen 28h blue bands. Like you said they have a 1:1 gear and a 1.5:1 overdrive, that being the case they were designed for 20" bikes (hence the need for only 28h). But, a yellow band kickback has the same internal design as the blue but with 36h shells and .67:1 and 1:1 gearing like the older red bands (for 26" wheel bikes). I took the big overdrive blue guts and installed them in a 36h yellow shell, then laced it to a 26" wheel. The result was a standard 1:1 gear and the massive 1.5:1 overdrive with a big wheel. Tons of fun if you live in a flat area, but it turned out to be pretty useless on a 50lb bike once I moved to Seattle
Some other details about the old kickbacks, I've found the red bands to have superior braking compared to the blue/yellow hubs. Also, the axles aren't threaded all the way through on red bands (they are on blue/yellow). When the shift mechanism spring thingy wears out, it gets locked into top (1:1) gear. To disassemble a red band you have to shift it into low gear, which is impossible with the worn shift mech, so you end up cutting the axle to get the thing taken apart. Fun! So if you rebuild a red band, it's smart to put a fully threaded axle in there.
