Rochester carb fuel inlet question.

[skillet]

I recently bought a Rochester quadrajet 7042200(1972?) on ebay, but it did not come with the fuel inlet fitting. I tried screwing in one from my 1978 carb(has the paper filter), but the '78 fitting would not screw in all the way into the '72 carb. and the threads did not look damaged. I know there is another type of fuel inlet fitting(one with the porous stone looking filter) and am wondering if that is the type of fuel inlet fitting I need or are do the two types of fuel inlet styles interchange ? Thanks very much for any comments.