I only ran one support do to room. I was the same idea, but I used the holes on the bottom and mounted to the cross member. I used the same poly bushings for the TC as I used for my motor mounts.
I went for over a year half of hard wheeling and comps with the atlas unsupported and never had a problem. The first trip out with the stak broke the th350 in half. I had it mounted the same way as the atlas. I added a support to the lower back RT to stop the twisting the TC will cause when...
I've had an atlas and I think it shifts the same for the front and rear hi an low. The shifting for the 3.0 to 5.41 is so smooth and easy on mine. Ive had the case for over year and half. The case isnt much bigger than the atlas II and the output for the front is over about a 1" which took away...
I really like mine. The one bad thing is it is really heavy and you have to support the back side of the tcase. If you dont you will break the tranny case.
I love my 3 speed tc and I dont think I will ever go with anything else. The 5.4:1 is great for tech crawling and the 3:1 for when I need the wheel spin to shot something.