everything I've seen points to any color ordered being done at the factory - I'd be a bit skeptical of vehicles being shipped in primer in the 40's, 50's considering they were shipped on mostly open train cars and trucks - aside from the fact that primer wasn't at all waterproof back then, some areas would be next to impossible to paint once the vehicle was completely assembled [firewall!], without dis-assembly - painting on everything was done before any assembly
fleet/special orders in company colors were [and still are] common - my 57 panel was ordered in a non-standard 'emergency yellow' for use as an ambulance - also had some windows installed in the "advertiseing panel" at the factory
Bill
