I recently purchased a P220 SA/DA police trade in from our friend "Garand man", and it has a smaller set of factory grips than my older P220. Can I still get the "old style" lager grips, and do they interchange OK ?
I can't try my old style grip on my newer gun because it is SA only.

If you mean the newer gun has the 1-piece E2 grip, you need to check whether the frame has the threaded holes for grip screws underneath the grip. Be careful, as many a trigger bar spring has been damaged by the removal or installation of E2 grips. If the threads are there, you should be able to get a set of 2-piece plastic grips and screws for it.

These are the factory "slim" grips, they are two piece, but are not as large as my other grips.
Will the old style SA/DA grips fit on the newer gun ?

Yes

They have the same dimensions on a '95 P220 in .38 Super as well as the new for 2015 10mm.

Not sure when yours were made, but they should fit fine.

The older, original style grip plates will fit, but good luck finding them. If you locate a source, please let us know here.

If you can't locate the grips you are looking for, Hogue offers rubber and wood grips for the 220. Perhaps one of those would work.