Please take a look at your Unitrons of 40mm and 50mm aperture, and post here if you find the objectives air-spaced or cemented. We are not interested in the 40mm finder scopes found on larger Unitrons, just OTA objectives from 40mm and 50mm models. Three foil spacers will be visible if air-spaced. No spacers and it is probably cemented. Please do not remove your objectives for this, unless you know what you are doing.
I have a 50mm model 105 from the 80's that is air-spaced. I will check my older 40mm and 50mm models this weekend to be sure, but I remember testing them as cemented. Stay tuned.