Crosley said:
there is not 2 grooves for the snap ring..
there is a small step in the machined sides that DIY folks 'think' is a groove... it is not.
then past that , is the actual groove for the snap ring.
After I re-arranged some stuff under the lift and got under there with a flashlight, I saw exactly what you were talking about, in the right light it LOOKS like a groove.
At any rate, got the boost valve in, and despite a missing hood (just haven't put it back on yet), small exhaust leak, and valves that need adjusting, THE CAR RUNS BEAUTIFULLY! Thank you very much for all your help!
Now if you'll pardon me, I'm off to go yell at the rebuilder: 2 weeks ago when I got the transmission back in and it didn't work, the VERY first thing I mentioned was "Hey, some people online said something about a snap ring under the boost valve?" and was reassured multiple times that it was simply NOT POSSIBLE that was the problem. At any rate, I've got some choice words for him... Word of advice, if you're in Denver, CO and want a transmission rebuilt, DO NOT take it to JCB Transmission in Arvada.
Thanks again guys.