Fixed stock compatibility question

Is there a specific buffer tube required to mount an a2 tyle fixed stock? I see that there is an extension but does that work for any or is there something required specifically. I'm trying to get something cheap and easy since I'm doing a .22 conversion and that's all I really plan to use it as for the foreseeable future. I have a diamondback db15 if that helps. I want to go the fixed stock route since I'm in NJ and anything else needs to be pinned, and I don't really like the look of what's on it now. Any help is appreciated 👍