The idea with the locks is that you can only lock the door with it closed. The power feature for the other locks should work since you are compressing the lockign switch but the driver's door button won't go down. Most people figure out pretty quickly that you can open the back door and push the (closed) driver's door button down to lock it without the key.
If any of the actuators don't work, they're not hard to swap out. I can't remember if the 240 lock motors will work but good junkyard motors aren't hard to find. The motors will freeze up solid if there's any water getting inside the door.
The power window switches should be interchangeable electrically between the two cars. The rocker part is going to look a little different, but they'll work if the 240 has good switches. OTOH all of them are pretty easy to repair. Just take out the switch panel from the door, pull off connectors, pry out the switch (careful of the housing, use a tiny screwdriver or penknife) and push the switch out. Pry apart the switch separating the top from the bottom. There are two coil springs, two BB sized balls and two see-saw metal tabs. File down the silver contacts until they are smooth and shiny again- they'll be all burnt and black and probably badly pitted. I used to be able to do this job in about 5 minutes per switch. We almost never had to get new switches for cars at the dealership.
--
Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE: 625K total

Here's a little trick I use quite often to see if parts are interchangeable between cars. I go to fcp groton's website, www.foreigncarpartsonline.com, and look up the part numbers for whatever parts from the cars I have available to me. So, in your case you'll want to look up a power door lock motor for a 85 740t, and an 84 240 whatever. If the part numbers are the same, you can swap em. Plus, you can see how much money you've saved yourself if it turns out that the trade is doable. Big fun!
--
1981 244 glt

The locks on the 700 are only locakable when the car door is closed this is a saftey feature to keep you from locking your keys in the car, it is normall for you to have to use the key to lock them. sticky locks are sometiems signs that the motors are going.

The locks on the 700 are only locakable when the car door is closed this is a saftey feature to keep you from locking your keys in the car, it is normall for you to have to use the key to lock them. sticky locks are sometiems signs that the motors are going.