Ok so I installed my ibu and worked around it. I am going to have to make the storage bixes in the floor longer forward than the real T12 had just because the ibu is that long. Maybe the ibu3 will come out and allow me to retrofit if its smaller.
i have the gun mount mostly made now. It sits in place and looks preatty good. Man that was a ton of work making it all out of tubing telescoping sections and making tubing corners and pinned mount points.
I had a linear servo I was hoping to install in the channel under the gun barrel for my recoil but the ibu wont operate it on recoil. Yes i tested the linear unit on a regular rx channel and it works and I tested a different micro servo on the ibu recoil port, that works, so im stuck with trying to get a micro servo inside the gun mount to yank the barrel back. The rotation servo will go in the ammo box under the mount as maybe a speaker too. Elevation, well Im not sure yet. Thats important, more than traverse.
time and trial will tell. The rx is up under the hood. Im going to flip the ibu upside down and run the cables out all through the floor and to where they need to go, aslo going to probably mount the battery under the floor between the frame rails. Thinking of using A size nimh batteries to make a pack.

Going to have to cut out the windshield to allow for prototypical elevation drop. Probably will be the last phase of this project.