I laugh because most of the folks replying are on the west coast or in non-rust areas....
Get with
@slow95z about a possible frame purchase and do a frame and axle swap.
Is this on the rear half only like someone used it for a boat launch and never washed it off?
You do have a lot of rust there to deal with and that means a lot of broken bolts. You need a lot of bottom end stuff there. Find a parts truck that's in good shape underneath.
Before you do this, though, you need to check your local laws on a frame swap because the VIN is stamped into the frame and now they will no longer match.