This has actually come up a couple times in the last few months. From everything I have seen, the truck frames ('74+) are the same between long and short beds, with the except of a little extra frame on the end of the long bed. The general consensus is that you can chop that off, rework your bumper mounts, and be good to go.
In my opinion, you're shooting yourself considering that '73 frame. A LOT changed with the '74 update, and all for the better. The rear springs are oddballs on most of the early-mid '70s frames. I think they might have settled on the last revision somewhere around '76?
You should have no issues converting, but I would suggest finding a bit newer frame.
edit: There might have been some moving of spring perches as well...I can't remember 100%. I know the spots existing in both frames, though. If you do need to move mounts, ranger spring mounts work for the rear (shackle-end) rear spring mount, and it's bolt on.
1983 J-10 - 4.6L(MPFI)/CS130D/Hydroboost/NV3550/D300/44/44/3.54/Disc-Disc/32s/42 gallon 'burb tank
Last edited by Cecil14 : 07-31-2018 at 12:29 PM.