I'll need to do some more investigating.
When I first saw this line dangling free I thought it was a good place to start but if it is just a vent tube then mounting it somewhere isn't going to solve my problem. I still wonder what that wire is bundled with it, it's pretty rigid like maybe 10 ga. Maybe it just had an eyelet for mounting the tube to the firewall.
As far as originating point for this line it's hard to say for sure since I can only trace it by feel but it does start somewhere on top of the T-case, so it starts at the T-case, runs forward on top of transmission, then starts to go up firewall on the drivers side and that's where is dangles free. The vent tube for the CAD is securely in place on the passenger side.
Not sure how much time I'll have the next few days to work on it so may be a delay here.
Thanks for the replies,