ok directional lever is on steering column
is it the mechanical type lever that operates 4 switches inside or is it the thumb lever style with the magnetic switch?

with this xm series i'm not sure if they incorporated the smaller thumb switch in that truck that early on, it does not show in the manual i'm looking at so i will assume not, so lets go with the mechanical lever assy that operates the switches.

you should remove the steering column cover and check those switches (should be 4 there) and see if one of them is stuck or adjusted wrong. From the sounds of it the truck is staying enguaged in forward. If you find no problems with the switches then your problem is most likely in the control valve solenoids not releasing (sticking).