They're only $18 if you do ruin yours. Mine was rusted in place but the pump was bad too so I didn't mind cutting it out. Here's a universal tank kit
I just left the switch out and wired it up to existing.
I should mention that the tank was held in place by a metal strap and there were two rusted self drilling screws holding it. Couldn't get them out so just cut the strap and then banged the heads off. I had to drill a couple new holes nearby for the new tank.