du-bousquetaire: the 6 wheel power trucks are from USA Trains. Fortunately they also made side frames that are used on one of their locomotives that look exactly like the 1-A-1's. I now realize you were referring to Passenger car trucks, The only ones I am aware of were made by Aristo Craft, maybe someone is holding some you can purchase.
Santafe 2343: Looking for the contact info for the Shark kits, will edit this when I locate it. LiG
EDIT: Gentleman's name is Robert Fern, email is [email protected]
. The kit he produces is for the more popular 4 wheel power truck version. I believe someone else produced a B unit kit, anyone who knows more please jump in. LIG