Only trouble i have seen with behind the plate with a 58 is you have to hang the tank a little low,it dont fill real quick and when full does the ole spray out the cap trick(remember at the drag races,even with a great cap they used to dump fuel but it was only 45 cents LOL). In the bed is cool with a brass boat screw on cap.But most put it in the rear fender,its high so you can fill it easy.
