[RickRado]

I have a 77 bayliner with a volvo280 outdrive, It currently has an electric tilt unit only. It doesn't work well in shallow water, because I can't trim it up, to get in and out of the shallow dock areas in Michigan. I've been trying to find a hydraulic trim/tilt unit to install, instead of the electric tilt cylinder. Is there anything out there that will work, if the original install was only that electric tilt cylinder?

[gcboat]

I really don't think you're gonna' have a lot of luck there. However, before you throw the towel in I'd be tempted to check your "throw" of the unit itself.
Might be a simple gear problem or the motor limit switch is going bad.
Tilt it all the way up (need it out of the water) and take a look at the remaining amount of gears that are left. If they are to the max height then that's all you're going to get. If there is some additional movement that could be used then check what I mentioned.