I have posted several times about the 210's in our local yards, but no one seems interested.
Before buying the Sierra transmission you should inquire how much it will cost to overhaul. Or were you planning to spend all that time and money shipping and installing a trans that might be worn out? If I was a scrap yard owner, I would be sorely tempted to send a less than perfect item to a place where the buyer can't get back to me with complaints and keep the best for my local customers. Not that that sort of thing would ever happen in the used auto parts business......right?