Before I knew about Jerry's reverse rock tumbling method (polishing the inside of the tumbler instead of the rocks) I used one of the sloshing compounds offered by a lot of the restoration houses.
My '56 Cadillac tank was done over 20 years ago and has had no problems with delamination or leaking.
The '64 Galaxie was done sometime in the 1990s and held up very well for 20+ years until a couple years ago when it started leaking.
In both cases new tanks were not being made for these cars so repairing the original was the best solution. The Galaxie had pinholes so a sealer was absolutely necessary.
The Cadillac was rusty but not leaking. The sealing system took care of the rust and it's still on the car today. I'd have used Jerry's method if I'd known about it since my dad had an 8N tractor at the time.
Check into the cost of a new tank vs sealing and or rock tumbling. If you don't have a tractor, rig up some sort of rotisserie to do the same thing.
