I have the following available. Let me know which ones you're interested in.
Snap-on 1/4 dr:
TMXKL110, 11 in, no ball, this one shows up on the Snap-on website as a locking extension, but the end is just a straight 1/4 in with a straight through hole. So maybe the locking end has disappeared.
TMXK4, 4 in, two available
TMX2, 2 in, two available
Snap-on 3/8 dr
FX8
FX12
FX2
Proto 1/4 dr, 6 in, 4761