The only difference between my gun and an 85 Combat is that the Combats usually come with an adjustable rear sight. My gun has all of the pre-B characteristics. It has the squared off trigger guard, where yours is rounded. It has the pinned front sight where yours is staked. It has the ring hammer where yours has the spur. My 85 also has the full length serrated spine on the slide where your 75 does not. Also, your magwell is a bit smaller and will not accept B magazines without alteration to the gun. In the little bit of testing I did with the 85 before it went in I think mine has that same issue.