For the unfortunate few of us whose TMs were built with separate black and gray outlets rather than a single outlet to the sewer line fed by black and gray valves combined in a single assembly.....there is a solution! Many thanks to tentcamper for directing me to the "Valterra T18 3" Hub x 1-1/2" Hub x 3" Bay with Cap Rotating San Tee Double Valve Assembly". Available from Amazon for $30
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I removed the old black water valve assembly leaving the back plate in place (no cutting!), then removed the back plate from the new black water valve, and attached the new combined valve assembly to the old back plate, (thanks again for the idea tentcamper.) I cut the 1.5" pipe about 5" from the gray tank. (There was no other place to cut since it was all couplings of one type or another to the old gray valve.) I added a union and a 90 degree elbow to short lengths of 1.5" ABS pipe to match up to the new assembly gray valve. Both valves rotate on the new assembly, so I moved the black valve handle 180 degrees away from the tire, and rotated the gray valve handle up and away for good clearance and access. The gray tank is slightly higher than the the black outlet so it was easy to keep a good gray water downhill flow to the combined assembly. Pics are before and after, sorry about the poor lighting in my garage. PM me if you want better pics.
Chipper229