Outer Limits 4x4 Board

Can i pull out my manual box from my 89GQ 4.2 turbo diesel and put an auto behind it? will it match up and handle the torque ok?

yes

I'm using standard auto for winch comps. I'm running 20psi, intercooled etc etc and apart from rebuilding the auto, fitting a shift kit and having the torque convertor strengthened, it is standard internals. You just have to remember that these autos have a life span of about 200k before they need some work done. Most people do nothing untill they shit themselves and then complain they are weak. In modified form they'll handle over 400kw's