It would be pretty heavily involved. First, I don’t think any 3rd gens had the Auto-Up function, just auto down for the drivers side. At least thats all that I’ve found. (Someone correct me if I’m wrong)
Fortunately, if you were to aquire some Auto-down switches—Not the whole board, just the switches, it may be possible. While the auto switch is a bit beefier, I believe the pins line up the same, meaning you could just take off the old non-auto switches and solder some auto switches in its place AFAIK.
BUT like I said, there’s still definite sizing differences between the two. You would have to do a bit of trimming on the switch bezel to make them fit. You can see on the left that the auto switch has a larger hole
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