Some of the junk yards I am talking to tell me that they wash the transmissions. I know that if one washes an engine, the spark plugs MUST be in, or water gets into the cylinders. Are there any precautions that need to be taken in washing a transmission to keep water from entering the assembly? Its on a 1991 Legacy AWD, automatic tranny. Thanks.

If it's still sealed up, the only entry point is the vent lines. If you change both the diff & at trans fluid when you get it, I don't think you'll have any issues.

 

For more precaution, after you have it in the car and driven around for a couple hundred miles, change the fluid again.