I used the POR-15 tank cleaner and sealer kit on my 48 and it worked like a charm. The tank was pretty bad inside. I was getting a lot of crud in my fuel filter. No problems now.
I've also read that some folks put some old nut's and bolts inside the tank after removal and shake the hell out of it for 10 minutes or so to loosen up the years of varnish and debris.
-Rich
