NICE!!
I just got a transit for work too. I have only had it a week. I have the cage behind the driver/passenger seats so the driver's seat doesn't go back far enough for me. I am working on moving the shelving unit back and then moving the cage back so I can get more leg room.
One thing I also didn't like was the small arm rest. The one that you built looks really nice! do you have anymore pics of the mounts?
Thanks,