Will any of the newer automatics fit behind the 300 six in a 1974 f100?

You have a rare transmission. A small Bell housing C-6 is hard to come by highly desirable to some enthusiasts because of it's durability and it's easy to trick out. 5 speed manual? You could but if it's fuel mileage your're after, buy a small car. You could install an Over-and-Under splitter unit (for about $1200) 5 speed auto? You'd have to change out everything but the long block and add the electronics to handle it.

Thanks! Not so much the fuel mileage, although any improvement would be an extra. If I purchase this truck, I would use it to pull a boat/trailer (about 3500-4000 lbs} and thought the extra gears would help getting up to speed and less wear and tear on the engine and transmission. I do understand the C6 is ultra strong. I'm also told the 300ci six should have no problem pulling the combo (3.50 rear end). Now to decide if I want to pay the price for this truck.

I used to pull a Jalopy race car, trailer and gear with my 77 Econoline - 300 six and C4 tranny. It'll pull it - won't win any speed contests but it will pull it anywhere you want to go.