There's a pic that PieMan posted in General Tech on 2/24/16 that I think will show the differences. I tried to link, but pics didn't follow.
IIRC, one of the threads gave the actual serial number when the change was made, but I couldn't locate that. I believe it was on the '06 790s. My 11/05 build date 790 has the newer design. Not sure about the 865s.