I have an engine hoist similar to this one:
http://www.ruralking.com/engine-hois...m-midwest.html

It's useful within it's range but I was thinking about making some parts to
adapt it for more height, so I can load and unload taller things out of the
back of my truck.

Referencing the picture in the link above. What if I removed the existing
boom and cylinder, installed 2 hand crank winches where the existing boom
mounts, and installed a longer boom where the existing hydraulic cylinder
mounts at the bottom end? The new boom might be made of channel iron, cut
and welded with some angle to "curve" the boom for object clearance. The
desired end result would be to stand the boom to where the load would be in
the same range that it is in the existing configuration but give high enough
lift to load and unload items from a pickup truck, maybe even off the back
of a semi.

Oh, the 2 hand winches, one controls boom angle, the other lifts the load,
snatch blocks could be used to half the speed and double the force. This
configuration would be less idiot proof since someone could lower the boom,
getting the load beyond the wheels, and flip the thing.

But all in all it might be easier to make an adapter for the existing boom
so it could be angled closer to vertical, and use a longer extendable boom,
then just add a winch and pulley.

Either way it should be a simple matter to go from engine hoist to a taller
crane by changing a few parts around.

RogerN