stylintrucks.com
I can't vouch for earlier models, but from 2000 on 2wd with coils up front the spindles are not interchangeable with torsion bar systems. the upper ball joint is smaller on the coil spindles. the upper control arm does not have a replaceable ball joint (on the coil systems) so the entire upper control arm would need to be replaced,,,BUT, the torsion bar compatable control arm is bigger and will push the top of the spindle out about 1/2". not sure if the holes in the frame can accommodate the extra 1/2", plus it will alter the steering geometry.
Perry