The current "Toyota" steering box is an aftermarket unit re-designed for these trucks. The original Toyota box mounted to a bracket that mounted to the frame. The current version mounts directly to the frame. The kit should include the drag link, pitman arm, steering shaft flex joint connector, and column bushing (for stock column). You also need a pump, pump mount brackets, hoses, pulley, & belt. It is also a good idea to replace the existing tie rod/tie rod ends with the newer type. The existing column will need to be modified or an aftermarket column can be used. However, It is not a simple bolt in.They work so well you probably won't want to sell it.
I get my steering conversions from ABS Power Brake in Orange, CA. www.abspowerbrake.com