My Father in law told me that back in the 70's it was poplular for people to who towed alot to put a second tranny after their main one. Like such: A heavy duty pick-up truck with a big V-8 engline, this would have an automatic tranny with torq converter as usual, but after the main tranny, they would mount a salvage 3 or 4 speed manual tranny to the main one. It would require some moderate brackets and adapters to be made, as well as new drive shaft, but the end result is that they could run the manual tranny in top gear and have a 1:1 gear ratio as normal, or any of the lower gears to get more low end torq when starting out towing. This all seems logical to me and possible. But I have never seen a build or even heard anyone else talking about this. Does anyone else know of such a set up? I think they did this on two wheel drive trucks mainly. I was wondering why not do this on a 4 x 4 and mount the transfer case after the second tranny. It seems like that could work also kinda like the doubler transfer case set up using dual tranfer cases, but this could provide super-crawl gearing.