According to their FB page, it will be going to replace chair 3, which is the beginner chair. That is the shortest chair they have, so there will be plenty of spare parts left.
They are also replacing the chairs on chair 5 with ones that have foot rests. If my math is right and the Windham F lift is 1500 vertical, there should be enough chairs to replace the ones on chair 5 and replace chair 3 all together and still have some backup parts for their other lifts and have a slew of old triple and double chairs to sell to the public. Snoloco may want to double check my math on this though.
They are saying the replacement of chair 3 will be next summer. The replacement of the chairs on chair 5 will take place before this upcoming season.
This is all just my take of it based on what I read on their Facebook page.
Ski the snow on the ground, not the date on the calendar. - Glenn Plake