I see a lot of dancing around the issue and things inaccurate.

You can use crystals from different manufacturers as long as they are made for that type.
You cannot use dual conversion crystals with single conversion radios and vise-versa.
If you got a dual conversion radio, ONLY get and use dual conversion stuff.
Let's assume that you somehow managed to get a single conversion crystal working with a dual conversion receiver. Do you really want to chance a mishap in the air?