Sorry I didn't see this yesterday! Fletcher wears this harness and is between L and XL. I use the XL for him because he has the "stocky" greyhound build, but if your dog is the lean and rangy type, you would probably do better with the L. The D ring should go just behind the sholders, so that the velvet part is straight up the sides of his body, if that makes sense? The WWW people are very nice about helping you adjust the harness if you call them, but it sounds like you really do need the smaller size