I have a 1986 F-150 with a 351 Windsor and a three speed auto and a low speed rear end, an old farm truck apparently. I am thinking of pulling the gas engine and auto tranny then putting in either a Cummins 4BT or an Isuzu 4BD1T 6 cylinder, maybe even an Mercedes OM606 if I could find one cheap enough. I'm also thinking about installing a manual tranny with the diesel like the ZF5 if I could find the adaptor plates for whichever engine I go with. There are two fuel tanks on the truck and I wonder about re-purposing them for diesel along with the fuel lines and tank selector switch. Has anyone done this with a similar truck and what are you thoughts of problems encountered and your solutions?