First off, we have a member here, Mike Forte, who's a transmission guru (see his banner ads as well). He'd probably be a much better resource than me for info. But then there's the search engine on your computer. Look up Tremec TKO. These are readily available both new and recycled, if you're patient you can hunt down a deal. They're 5 speed, have three options for shifter location (fore and aft), and are well proven. Again they're available in various configurations up to at least 600# torque rating. To my feel they're a bit notchy on the shifting, so might not be the best for drag racing, but that doesn't sound like what you intend. Another trans from Tremec is the T56, six speed, two overdrive gears if I remember correctly. The prices on these are a bit higher because of demand and the limited number of cars they come in. But it's another option. Personally, if I were going for towing I'd stick with an auto, but then I'm a lazy old man. I don't mind shifting in the rods, but in my truck I'd rather sit back and enjoy the ride.