Thanks guys.

Yes, this is an in-ground pool, but in preparation for resurfacing, I've pulled the old niche out myself and ordered the plastic Pentair niche, which will hold the Intellibrite 12V LED that I'm converting to. Looks like it should fit fine. Honestly, I don't understand why these pool folks feel the need to give unreasonably high quotes for things like a light replacement. All the parts - light, niche, and controller - are on their way; total was $730. They want me to believe that installation will run over $2100? Uh, no, I think I'll shop around...