There were special off-catalog runs of these made for Davidson's and I think Lipseys?
Not many...1,000 of each variant, stainless and blue. I think.
You CAN "roll your own" any of several ways: find a factory 45ACP cylinder and add it to a 45LC gun. Odds are about 50/50 or a bit better that it'll drop in without "fitting" - use the "checkout procedures" to check endplay and timing issues...if it's off, any decent gunsmith can sort it out.
Can't find a 45ACP cylinder? Find a lesser caliber Vaquero or Blackhawk cylinder and have it reamed bigger to whatever caliber you want. Check it's timing and endplay issues first - although the bore will be smaller, you can still check for the "circle inside circle" alignment and endplay.
Oh ya: if you're not picky about looks, yes, you can run a stainless cylinder in a blue gun "palimino".