Starting to sound like your options are severely limited. If it was me I'd pick up a 2 something open 8 3/4 chunk for daily driving and swap in the 3.91 for track days. Shouldn't take more than an hour or so to make the swap. You should be able to pick up an open chunk fairly cheap. I paid $175 for a 489 case 3.23 open that had just been checked, cleaned, and had new bearings installed. You should be able to find a 2.76 or 2.94 in that price range. The open rears are almost give aways for some reason. I'm assuming you have an 8 3/4 in your GTS, haven't seen one yet that didn't. Hope this helps and you find one under the tree.