Nice truck. I have a standard cab, "65 F100 with the 300 six. Bad to the bone. I have the efi exhst mnflds. My truck weighs 5,300 lbs. I have a steel plate for a fab table and a Miller engine generator welding machine behind the cab. I gained lots of power with the efi exhst mnflds, two plain jane mufflers, then two short pipes that turn out before the pass rear tire. Bet a 300 six would do great in your dump truck too. Not that the V8 isn't a good engine. I'm partial to sixes is all.