Sniper,
There were several vintages of Contender frames made between 1967 and TC unceremoniously dropping the model with the new millennium. Some of the easily noticeable differences in the "original" frame types were various firing pin selection systems, a change in the barrel pin location and in the breech block design. While there were some "flat side" frames made, all of the original production frames had a cougar on them. Up until 1996/97 it was basically a deep relief full body cougar and after that an etched cougar head only. The easy open frames started in late 1981 and continued until the demise of the original model. Stainless frames date from 1993, were all easy open, and all had the etched cougar head. In 1998 TC changed to a new breech face idea with mixed results. The concept of a replaceable wear block may have been good, but the first frames incorporating it were problematic. Some needed to be sent back to TC for rewelding. The demise of the Contender soon after put an end to TC ever getting the bugs worked out.
Can't help you with the G2's, sorry. Tim P. sneaked the prototype out from under the table for me to play with discreetly at the 2000 SHOT show, and I knew right then I would never own one (and told him so).
L.