I'm not sure that Gaffney (as much as I love them) would take this on. My experience is about all they will do on a CAT is change filters, oil, etc. When my CAT had a sensor issue they sent me to Carolina CAT in Charlotte. Folks here said that was a good thing because CAT doesn't share the diagnostics to non dealers.
But, it is an interesting subject because I don't know if CAT (or Freightliner) will touch the Allison. Please tell us how this works out.
Hickory, NC. 2007 Fleetwood Discovery 40X