[Mr V]

One thing to keep in mind is that window, seat and door motors are not designed for a 100% duty cycle. Wiper motors are.

The strongest motors you will find will be those for Ford and GM Suv's and Chrysler minivan's "5th door". Those have to lift a ~100lb "door" w/o the benefit of much leverage. Can't say I've ever messed with one and held it in my hand though. As long as the recycler writes door instead of hatch on the receipt they should be legal, guess it depends on their and FIRST's definition of the opening on the back of such a vehicle.

Sliding door motors do move a heave door but they are sliding on tracks not being lifted.

Next will be window motors from older GM and Ford cars, up to late 80's/early 90's depending on model, they have near CIM sized motors and have to work against a very strong spring to lower the window and their mechanisms are kind of crude. Pivots are often steel on steel w/o grease after the first few years. Both are quite durable too. The problem is that they incorporate a safety feature in their drive mechanisms to limit torque. In the Fords it's a plastic gear that wears out and gets brittle with age as do the "rollers" that transmit the power to the output gear. Their failure rate is so high that you can walk into most auto parts store and find the gear set in the HELP! Section. Depending on the model line they are found in up to early 90's vehicles.

Seat motors from the older (similar age range as the window motors above) GM and Ford cars are also quite large, again they are near CIM sized and the tilt/height motors work with little leverage to lift hundreds of pounds.

Wiper motors aren't a good choice IHMO, often they are grounded through the chassis since they aren't intended to be reversed. The park function could be useful for some applications though but could make for problems should you want to try to reverse it. You will want one from a vehicle that doesn't hide it's wipers under the hood as they often have a secondary gear train so they stay in the "up" position when used on the intermittent function. Also note that many have an unusual way of obtaining low speed. Power is required on 2 wires for low speed and 1 wire for high speed. Many late model GM wiper motors incorporate an on board processor to read the resistance of the switch circuit in a particular position to determine it's operation.