I put about 1.5 gallons of herculiner truck bed liner in the jeep.  I started roughing the paint with their weak pad, but switched to 80 grit after about 15 seconds.  I wiped everything down with water, then MEK before painting.  Its 3 coats on the tub and 2 on the roll bars.  This should keep the tub rust free for the many years i plan on keeping this jeep. 6-9-09