I have a 60T venom fireball with the integy not quite 4:1 gear reduction on my IH5900 heavy haul tractor . That truck did very well in the sled pull at Indy . I used to have a 75T integy lathe in it with the "4":1 was just too slow and ripped the pinions apart in the rears pullin me around (180lbs)
. I've only ever used integy lathe or the venom fireball so can't comment on the rc4wd