Yes,
You should be able to take it off the 1250 and put it right on the 108. They are both wide frame tractors... They are from 2 different model series, the 108 is from the 86, 1x8/9 Series and the 1250 is a Quietline - 800-1650. They use basically the same frame (not exactly the same frame, but very similar), but when it comes to attachments, they use the use the same ones.
So pull the PTO to deck belt, the mule drive/undercarriage and the deck from under the 1250, and move it all over to the 108, and you should be out mowing in a few minutes.....
We have the moved the belt/undercarriage/deck back and forth between our 149, 1450's and 1650's....