Gary, your M152CDN is a panel van so hope as you may, you will not find evidence that it was an ambulance. The M43CDN was the Ambulance. Google M152 truck or M43 truck and you will find some information. Likewise Service publications has a nice little inexpensive book ($10.00) on the Canadian 3/4 ton series under the Weapons of War series.
http://www.servicepub.com
ED