well you can get the smog pump eliminator bracket from a 5.0 and bolt it in place then belt size wont matter. otherwise you can take a piece of rope/string and route it bypassing the smog pump and then measure and use that as reference at parts store. Or you can search on here, i am sure its been mentioned. remember you will have to remove the rest of the plumbing and plug the holes in the back of the heads.