What are you using the truck for that justifies swapping out a 5spd for a 6spd? My '96 had the 5spd, my '00 has the 6spd and the 5spd shifted much, much better. My dad now has the '96 and since he increased the power he's had no complaints about the gear splits on the 5spd while towing a ~13. 5K 5th wheel.
Brian