Love my new smart batteries and charger from Spektrum, quantum leap in control and convenience, traxxas makes a similar deal but either way you're getting well supported, cool stuff- depends on what connector you like/have.
My posting privileges may still be zero- forgot my mind and email when I sold my 80 series and can't get back into my original account- anyway; maybe there's the trans/axle combo?
I'll search, cuz I'm a noob again, but maybe that helps?
if you just want to rebuild it quick and dirty to get moving again run a bit of green scotchbrite - like a half inch strip three inches longish, take that and twist it around a drill bit or nail or something in your cordless drill. take the guts out of the master, run that scotchbrite combo in...
https://www.nengun.com/oem/toyota/
found this in my research today- I'm looking at a LY151 firetruck and trying to find details on what axles the lightweight DYNA trucks use.