What is a 42RH Transmission?

There are several folks using the RH42 behind smallblocks here (including me). As stated above there is work needed to the torsion bar carrying frame member along with a serious heavy duty crossmember to take up the slack for what you cut out. That is most easily accomplished using a US Car Tool crossmember that they offer for an A516 in an A-body and modifying it. Yes you need a shorter driveshaft. There is only some mild massaging with a large hammer on the floorpan, that you will forget about once the carpet is in the car. No cutting and welding of the floor.

This trans is probably not the best for a very high horsepower motor, but for a mildly hotrodded 318, 340, 360 it is great. In addition to the serious overdrive 4th gear it has lower first and second gears than the old 904 and uses a lock up converter. I can cruise at 75 on the interstate at 1900 rpms.