Here is a Venture Uni-Form Natural White 350W base-up open rated metal halide with UV shield. I received this lamp from Mike in his McCann Lighting lamp sleeve. Thanks again!
No problem. These were used in the Holphane Prismalume fixtures my grandpa gave me. He gave me six fixtures and about a dozen lamps. The 320W PSMH was in your M-400A2. Sorry I'm taking forever to box it up. It hasen't gone anywhere. Still save and sound on the couch in my basement, now in the company of a silver M-400 and a OV-15 TuDor FCO. I also have a PC to go with your M-400A2 and a lumiline lamp.