I have a 79 f-150 custom that needs a new bed, would I be able to use a different bed from a different year or does it have to be from the same year??

 

1973-1979 F100-F350 will work except for short box trucks.

 

I think the fuel filler door came in around 77, earlier had just a cap. High boys and SCS had different frame width and length, but you probably won't be tripping over them anymore.

 

X2 worse case a 73-mid 77 2wd or 4wd long bed (NONE highboy) will easily work. A HB will work, if will have different location mount bolt holes in the bed due to the HB having a harrower rear frame section. And a Camper Special has a different wheelbase and the large spare tire place in the bed side. And then yes late 77 to 79 will have a gas flap.

 

Other than the odd 140" wheelbase Super/Camper Special beds with the spare tire in the side, any bed from a 1973- 1997 f150-f350 will physically fit, you might need to drill new holes in the bed if it's a HB bed. You can even put 73-79 bedsides on the later model beds with a little effort.