Does anyone know how reliable these drives are, if they can be upgraded with new internals, and if they even make a diffrence in performance?

They can make a big diff in performance on the right hull.

I remember reading here a while back that some parts were interchangeable but do not remember with what.

what boat?

Thanks BY, the boat is 303 Formula SR1, I have heard so many diffrent stories I am not sure what is true and what is myth.

The hull has to be designed to work with the Blackhawk. I think they were adding rocker to the hull to make it work. The cats worked, I think..
They will accept an X gear upgrade kit, but I have not done one.. just saw one that had been done..

Hope that helps...

Know they worked well on the 29 scarabs. They made a limited run of them. I think everyone has seen a p29 somewhere.

do you need a lot of positive trim running now?

if so the blackhawk will not work for you.

Thanks for the info so far, actually I am looking at a boat that has this set up, It is a factory option so I assume that it works fine but just a little concerned since there are so few around.

Before you buy, call around and check the price on lower gears and props. You mat be a bit surprised.

true,props are not cheap

a 303 formula with BH drives? I cant believe they were factory on that hull. With newer gears, they are pretty reliable( I have 160 or so hard hours on mine now ) but thats on a 4000lb cat. I can't believe they would work on the formula because that hull needs positive trim to carry the nose. BH drives don't do diddly to lift the nose, they actually lift the stern.