91 would be a EFI (electronic fuel injection) vehicle , so you'll need the engine , engine wiring harness , and computer ,and possably the incab harness from the f350 , you might beable to modify a 5.0 harness to work , tho it'd be easiest to just use the 7.5 harness , keep in mind the 460 is not gonna just drop right in without some work , and your most likely going to keep a body lift to clear the much bigger engine , bigger transmission , ect , plus depending on if the donor is 2wd or 4wd you may need a duel sump oil pan to clear the k member...