I used a 87-91 Blazer 31 gal tank on a short bed.
Took fair amount of work for it to fit. Had to take out the spare carrier crossmember, move rear member all way to end of the frame, add 3" to the rear frame rail and notch the cross sill on bed itself.
And remember the filler is on passenger side. Worked for my idea but some might not like it.
I wanted it as tucked up as possible. Tank hangs down 7" from bottom of the frame rail.
The filler neck comes over the rail and landed exactly where I wanted it.
I welded a '72 Blazer interior fill hole inside the bed then made the neck exit like a K5 but on passenger side.
I wanted it to look stock, just on the wrong side. It all lined perfectly.
