I found the adapter from the tank to the 1 1/2 piping was broke just inside the tank neck. It appears the prior owner attempted to glue it back in with sealant and there were some cracks in the joints on the down leg that were cracked as well. There was some form of sealant applied over those too. I am assuming either he used the wrong stuff or did not clean it adequately for good adhesion.
Either way, it worked long enough to trade it or sell it outright to the dealer.
I got new pieces and the most difficult part was getting the length of piping adapter out of the tank neck. I was half tempted to just pound it into the tank but then thought I may end up having a problem with the level sender. I just spent hours trying to extract it. I finished assembly yesterday and am now waiting the 36 hrs of complete cure time before running water through it. In order to avoid possible flex issues, I installed a rubber drain connection to allow a little give. I also opted to replace the slider valve since I had the thing apart. No sense going through all the work to have a valve seal fail next.
I'll be ordering that tape too.
Thanks again for the advice.