As far as the tank, a tank from a Ramcharger can be made to fit (biggest hurdle is swapping crossmembers). Having the tank in back, rather than the side, gives the truck a better ride and makes duels a snap. Only downside is that it does away with the spare tire mount.
If you used a tank from a same year Ramcharger, you would have the intank pump setup your TBI truck needs.
