Well, the CR 40-2s were from the "mid production" time period. Of course there's the truck issue, but aside from that, the only reasons I didn't start from one for my 6366 were the ditchlights (wrong for my era) and the fact that the kato models don't have rear numberboards.
I know Robb will (rightfully) point out some smaller differences between these units and the prototype, but I think they'd be close enough for me.