I shared this inquiry with the San Jose (CA) Fire Museum, and got this response:
My experience has been if
they don't have a title a bill of sale form from the DMV(not sure what
state we are talking about) needs to be filled out by the seller in
order for them to sell the vehicle. Some forms even require a notary to
verifiy the certificate of bill of sale.
Its not easy to do and
dealing with the DMV doesn't always go as plannned. if they can find one
point of contact and work with that individual throughout their selling
of all the vehicles that is the best way to go because they may get a
different story every time they go to the DMV
I wish them luck.