Keith,
Here is what you were able to find on the white combo that was converted to an ambulance:
"Thanks for posting this, Kurt. Interesting car. But, it isn't and never was an ambulance. The patterns on the rear compartment windows are not Flxible and were probably added sometime later in the cars life-span. This is an FB23-748 - a 1948 Flxible-Buick combination car. It was Flxible's body number 15998 which was delivered to the Dunsford Funeral Home in Dodge City, Kansas on July 15, 1948. The motor, body and frame numbers all match what Tom McPherson found for this car in the Flxible Production and Delivery Record book. Now, I am wondering about the car sitting next to this one. Another Flxible but, it would be nice to see more of it and to get the numbers from that as well."