those look like longbed figures Jroehl
I think the front tank shortbed SC is 16 gal and the reg cab is 19. The rear tank is always 18.2 gal. Thats for the F150 which I don't think changed for the F250, did it?
1990 F250s didn't come with a shortbed. Reg cab long bed (133" wheelbase) or Supercab longbed (155" wheelbase) were the only options. The 16.5 gallon tank was only on the shortbed F150s in the front. F350 chassis-cabs and F-Superduties came with 19 gallon tanks front and back unless they had a diesel, then they had a 20 gallon front tank (except the DRW chassis cab F350 diesel, which had 20s front and back).
I've got the 1990 manual sitting right here...any more questions?
Or, what engine is in the truck, and what is the GVWR?
P.S. I just saw in another thread that you have the 351W--that means you definitely don't have the Mazda, you have the ZF. The Mazda doesn't fit the 351W bellhousing pattern (at least not from the factory).