Hey Jumpwings -
First welcome to the Forum. Folks here have a lot of info regarding medical stuff.
As for plasma bottles, do a search
for plasma. There have been several discussions about repro bottles already. Ebay sometimes has a guy selling a repro bottle but know about its quality.
Good luck on the ambulance. What model do you have? You can check this prior post on WC54 medical equipment
or the article on Ambulances
if you are looking for the medical components. If you haven't found it yet, the WW2 Dodge forum
is a great resource for the vehicles themselves. There are several articles specific to the WC54 and its 1/2 ton siblings.
Is there any specific info you are looking for?