Drive Assembly Sprockets are Custom Bored

[Mark Pettit]

We just took our transmission assembly (out of the kit) down to Bearing, Belt, and Chain, Inc. thinking that we could get a couple of more sprockets that would fit right onto the assembly so that we can get our machine driving by this weekend. They informed us that the sprockets for these are custom bored (as designated by the "b" in the model number). They said that we could use standard keyed sprockets but if we did that we would have to have them pressed onto the shaft.
We thought FIRST was doing us a favor by making a ready to go tranny/drive assembly, but if we want to go four-wheel-drive with a different sized sprocket, then we're pretty much out of luck. I can't figure out why they would limit us like that, but maybe you (Chief Delphi Participant) can shed some light on it?
Update: And to get the same "custom bored" sprockets from IFI will cost us an additional $80 for about $14 worth of sprockets if they weren't custom bored.
Whaaaaaaaaaaaaaaaaat?