Izzy's daycab inspired me to build a Tamiya 2 speed with all the upgrades. So far I have bought the brass helical gears, stainless synchronizers, aluminum case and aluminum heat sink end plates. Not everything is here yet though. There are only two other upgrades I can think of, a new longer shaft so you can drive off both ends of the trans mission and a PMD 4:1 reduction. I shouldn't have spent all of this on this transmission, I should have just bought a Veroma 3 speed with built in transfer case and had a better transmission.
I did have a hair brain idea, what if you had the longer shaft and a reception on each end of the transmission? Would be cool, but too long and too expensive. Again Veroma!
And here is the Veroma;