Jerry,
Why is a manual transmission a big mistake? I would think it would be preferable for efficiency. No torque converter to waste power, more gears typically than automatics. I have been dreaming about the Richmond Gear 6 speed OD. They are built specifically for heavy duty applications in Chevy trucks, yet they are as smooth and quick as the old T10s or Super T10s. I know they are spendy but to my thinking scrimping on the tranny can ruin the vehicle.