Well, In the last two days I've found something interesting. As of this moment, the dual return reservoir is not available anywhere unless someone has an old stock laying around. Aparantly all teh current stock is screwed up on the part numbers and you can only get it as a completepump, but you can't get just the cover. There's only basically one outfit that makes them and sells them under a handful of names and the current catalogs are ALL screwed up paper and computer. I went to napa and they got me one and it came with one return, checked and double checked all the numbers sure enough it's supposed to have 2, they checked teh warehouse, it wasn't a fluke, they're all that way, had the guy at Advance order one in, their picture showd two returns, it came in this morning with only one as well and identical packiging although supposedly different manufacturer.
So I'm out of luck for having a dual return tank unless I can get my plastic welder fired up and attach a nipple to the tank. in the mean time it looks like I'm going to have to T the return lines together. Gates lists that as an acceptable plumbing setup for a hydroboost installation, so I'm good with it.