Big Foot is a high thrust motor with a higher gear ratio. I think it is 2.42. Should work, but you need to take this into account with prop selection. One advantage of the bigfoot is they are less likely to have cavitation problems. Another is that they lower unit is in general a heavier duty than standard lower units.<br /><br />What does Merc make? They have pretty much phased out yamaha from the midrange 4 strokes. 30, 40, 50, 60 for sure and the larger bigfoots. This is a deal where they have done some conversions every year. This can make it tricky to figure out what is merc powerhead and what isn't. Merc and Yamaha are pretty much going different directions after the lawsuit. Merc lost the suit, but they bunggled up the supply on japanese motors this spring.<br /><br />Hard to say on the chrylser in terms of performance. I would say the bigfoot is generally used on pontoons, and workboats. If you want performance, you may want to look at the 50EFI or another motor with some thing like a 1.8 gear ratio.
