There was a post in the Dune Buggy Tech Center by MyBlueBuggy labeled "Deciphering a Meyers Manx serial number"  3/8/11  that listed Manx paint colors. 

On the list are 2 greens in solid colors:  31S Lime Green, 32S Dark Green.
and 3 greens in metal flake. 19E Spring Green, 21E River Green, 23E Sea Green. 

Interesting reading but does not say which colors may have been on pre-serial number cars after the Mono bodies.   I would thing fewer or different  colors than on the list is a possibility.  Still more questions than answers on pre-serial numbered square back cars.