http://www.imcdb.org/movie_74923-Mother,-Jugs-and-Speed.html

I don't know if this ambulance is the 1962 Pontiac Ambulance requested in main page of this movie.
I got from youtube this picture and there says it's a "Cotner-Bevington" ambulance.
I leave you here two links with more information about this type of ambulance
http://www.coachbuilt.com/bui/c/cotner_bevington/cotner_bevington.htm

http://home.comcast.net/~oldsfan/MySite/62cbambulance.html

And now the pic