Agree with Billy, as far as the US is concerned there were West Coast and East Coast bikes, from what stories you get on the penton forum. West coast coming in as KTM's not Penton. So the west coast ones were using the European colours, which meant for example - Red KTM MC5 250's compared to the Orange Penton 250's.
Then here, 77 MC5's that Brad Lewis has are Blue! I do believe the 76 MC5 400 he has is white and must be one of the early ones.
I am rebuilding mine to white.