I love the roof diagram! Byrd Ambulance, a/k/a "Zanesville Ambulance Service" and "Mansfield Ambulance", only had one 54XL that I know about. They also had a 1974 M-M Criterion, which was their only M-M they ever bought. They were a well known and very loyal Superior customer, in 1971 there is a beautiful fleet shot of all 13 of their brand new all-white Superior Cadillacs posed at the local Cadillac dealership just before being placed into service. 9 of these beautiful cars was a snow-white combination with a single beacon-ray, and 3 of them were 54" Superior hightops. They replaced all or much of their entire fleet every couple years, and continued buying Superior combination cars well into the 1980s even as all other ambulance services were ditching their Cadillacs in favor of the up-and-coming vans, Suburbans, "fat Alberts", and modular rigs. Byrd ran distinctive equipment, they also had several Cadillac limousines, and straight hearses, and first-call Suburbans with blanked out landau bars. They also had fully customized luxury vans outfitted with a cot, and rear patient area for long-distance transfers of non-emergent patients. As time progressed into the 80s, Byrd Ambulance was forced into retiring all their Cadillacs, and replacing them with the newer "trucks". But Jess Byrd, the founder and owner of Byrd Ambulance was known to lament the passing of the torch from the soft-riding Cadillacs to the rough-riding trucks. He was even known to tape record patients' rough ride complaints as they were transporting them to the hospital, and played exerpts of some of these to members of congress when he testified in front of the house select committee on EMS standards! I am working on a detailed article highlighting the proud company history of the Byrd Ambulance Service, and plan to submit it for consideration to The Professional Car. I only hope I do the company justice, as they were one of my favorite proud old names in the annals of EMS history.