[chris vickery]

While it is possible, the truck wearing an Allied Invasion Star being in N.Africa is highly unlikely.
According to official orders, the Invasion Star was painted on Allied vehicles just prior to the Normany invasion, seeing use in NW Europe. The Allied forces were also quick to paint ver these on the continent after the invasion as they made great targets for German panzers.
I do not think I have seen period pics of vehicles in Italy wearing these stars not N Africa for that matter.
American vehicles in N Africa did have the star on them but I have a hard time believing a HUA would be assigned there, especially wearing a US star.
The "77" denotes 9, 18 or 23 Field Ambulance of either 1st, 2nd or 3rd canadian Infantry Divisions respectively. The "77" should be painted over a black background.
Also there should be a divisonal sign opposite the "77". This would help identify which division it belonged to.
You may also find marking prefixed with a "H" to identify which truck out of the unit this was. Typically H1, H2 etc. It should appear on the doors someplace.
If I recall correctly (tell me if I am wrong) the 1st Canadian Infantry division was in the italian campaign during the Normandy invasion. The second and third landed at Normandy, so coupled up
with the Invasion star I think that you should find Divisional markings for one of these. I would suggest in all likelyhood, probably 18 or 23 Canadian Field Ambulance.
Your divisional marking would probably be a maple leaf on blue or grey background.