I went to the local junkyard... For $25 each they have tested take-outs with no warranty other than if you get it home and it's junk, they'll give you another. (If asked, they'll bust out the tester for you, so you can see that they're good batteries before you take them.
Better yet, for $35 they have "reconditioned" batteries with a one year replacement policy. I figured this was the way to go and got two similar sized batteries. They start the deuce great, and though one proved to be week when I cranked on it for a while w/o the fuel pump running (bad connection at the tank), it was replaced free of charge with one that they tested before giving it to me. (I didn't have them tested when I picked them up, so it was probably weak when I got it.
I figure that no more than I use the truck, the batteries are going to sulfate and die early anyway. So for $70 I got two healthy batteries that whip the deuce over just as well as 6TL's, if not better!
Just an idea.
C