This topic has been discussed often here, run a search for IFS lifts.

I myself have been running the Trailmaster 4" since '94, and with the exception of having to replace the idler arm(common on all lifted IFS, or hard wheeled IFS rigs), the lift has performed flawlessly. Some people here have had poor experiences with the Procomp lifts.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed