The model # indicates both guage and choke type. the last 2 digits indicate guage, *83= 410, *85= 20ga, *93= 16ga, *95= 12ga. The lfirst letter indicates choke type, K= C-lett choke (aka poly choke), D= D-tachable choke (external choke tubes). The last of this line was only discontinued a few years ago, the 695 12ga rifled slug gun. I'm not sure how similar it was to the originals, but they stuck with the guage designation.
I have a 185D, it's a beater, but it is reliable and it has never lt me down.