When I had a Rodeo with the same transmission as yours, I changed the fluid several times in it. Not fun. No matter how careful I was, I always ended up in a pad of ATF with my work closes wet.

ATF tastes no good.

But it's doable. Considering the sencitivity of the truck to the correct ATF level, it has sence to do the check/change yourself.

It's not a rocket science. Just find a manual (haynes or else) and do exactly what they suggest.

Oleg
Axiom 4WD 2004: OME shocks, 32" BFG Mudders, RockSliderz, OME929+2" spacers, Stinkyfab bent RE rear links, front ARB locker, rear No-Slip locker, DOR front axle lowering kit, custom middle section skid plate, IronMan torsion bars.
Deceased Rodeo'02 4WD.