Wanting to shorten bed on an 83 Diesel.

[mofoco12]

Wanting to shorten bed on an 83 Diesel. Mine is a single mid tank 2wd model. I already have the short bed with single mid gas door location. So the ? is, the single cab short bed trucks have s specific tank correct? I assume that the longbed and extra cab truck use the same one? I already checked and I have an 8" flat area to cut the frame so that's not an issue. I know this is long shot , but hope you can help. How a Great Christmas.