I have the following NWSL parts new (never run but test fitted):
#250-6, 25 to 1 Idler Gearbox, 3/16" axle
#251-6, 25 to 1 Gearbox, 3/16" axle
plus a few odd parts from a #495-6 universal coupler set
You can have it all for $10 plus $3.00 postage.
I'll be going into the hospital Monday 8/26 for a few days, and won't be able to respond after 12 P.M., but its not going anywhere. Let me know one way or the other.