aux fuel tank mount ???'s

[garage C20]

on my '79 C20 the PO had installed an aftermarket drivers side plastic fuel tank. the tank is split and wont hold fuel (no surprise HUH). while i was under the truck i noticed that the mounts holding the aftermarket tank looks like plumbers strap holding the tank in place. i looked at LMC's catalogue. they do not show fuel tank mounts like my factory pass side tank. i plan on replacing the plastic aftermarket tank with a 20 gal steel tank. do i need to find factory tank mounts? my pass side tank is a 16 gal and i would like to swap it out for a 20 gal as well. can i reuse the mounts i already have? i need to have a bunch of fuel for long trips out into the desert.