I am new to working on boats. I recently bought a boat that needed a new out drive. It is a bravo 3 that needs to be fixed. I think someone has replaced this before. My question is can bravo outdrive upper and lower be swapped ? For instance using a Bravo 1 upper on a bravo 3 lower. And for some reason I think this outdrive is a 2.43 gear ratio in a small light boat with 24" props. It has a strong running 350. I am trying to get the drive prop combo to cruise at around 3000 rpm to 3500 rpm. Any information would be gr8.

Yes uppers and lowers can be swapped with limitations. The older drives can only do it with certain models. See pic





Also need to pay attention to the gear ratios

youll need a 1.65 bravo one upper

On a small, light boat 24 pitch props and 2.43 gears doesn’t add up,
2:1 is a popular gear for a b3 and you’ll see them run 28 pitch props
on boats as you describe

If it has 24 pitch props, I’m guessing it has 1.81 final gearing
( 27/29 tooth count, the same as a 1.36 B1)