Ok, excluding fancy bomb hoists and HIAB's, there are, more or less, 3 choices on the market.
There is the Harbor Freight/Northern tool tall one, which is what Ryan Gill and I have. It features a hand winch on top and a hydraulic ram to lift the boom. We'll call it #1 and I will caption the pics as such.
There is a shorter version, such as what Armyman30+years has. It does not have a winch, simply a chain to which you can attach a chain hoist, etc. to. We'll call it #2 and I will caption the pics as such.
Then, there is the Cummins tools version, which is what Mangus580 has. I actually bought one of these first and tried it out and decided that although it was by far the nicest of the three, it didn't really suit my needs. We'll call it #3 and I will caption the pics as such.
#1
Pros:
A. Since the vertical post is straight, you can mount the baseplate right next to the wall of the bed, thus leaving more room for wide cargo. You can also get it close to the rear edge of the bed as well, thus allowing more reach with the boom (extended) or more weight capacity with the boom retracted.
B. Uses a pin/clip to keep the mast from rotating, better than the screw/friction arrangement on #3.
C. Hand winch and hydraulic ram lift offer multiple means of raising and lowering cargo.
Cons:
A. The hand winch that is included is only good for about 400 lbs., as I stripped it picking up a Deuce front winch at Aberdeen. Of course, better and stronger replacements are avilable at Northern, Harbor Freight, etc.
B. Can not use troop seats
C. Does not have a bearing for the mast to rotate on, so under a heavy load, it may not rotate as freely as desired (although it does offer a zerk fitting for lubrication).
#2
Pros:
A. Since the vertical post is straight, you can mount the baseplate right next to the wall of the bed, thus leaving more room for wide cargo. You can also get it close to the rear edge of the bed as well, thus allowing more reach with the boom (extended) or more weight capacity with the boom retracted.
B. Uses a pin and clip to keep the mast from rotating, better than the screw/friction arrangement on #3.
C. Due to it's shorter height than #1, it may be possible to retain usage of the troop seats.
Cons:
A. Does not include hand winch like #1, although it could be added.
B. Due to the boom being so much closer to the bed floor, the ultimate height cargo can be lifted to is limited more than cranes #1 and #3.
C. Does not have a bearing for the mast to rotate on, so under a heavy load, it may not rotate as freely as desired (although it does offer a zerk fitting for lubrication).
#3
Pros:
A. The biggest plus for the Cummins style is it's rotation method. The boom and mast head sit on a tapered roller bearing, much like a front wheel bearing. This allows an extremely smooth rotation at all times, but especially under load. I really miss this feature most of all.
Cons:
A. Mixed bag. The spine is angled back for balance and strength, but this also means that you have to move the baseplate further in from the bed wall and further back from the rear edge, thus cutting into cargo space and effectively making the boom shorter or reducing it's lifting capacity (if you have to extend the boom).
B. No hand winch, although you could add one.
C. Can not use troop seats.