the 'ms' would indicate a 1942-45 1.5T+, a 46 would be 'os' and that's what the vin decoders are going by ... it was the practice back then to title a truck by the year it was first registered ... and trucks built from 42 on were really mostly assembled from 41/42 production parts - if you get the number cleared up, don't confuse them about the year, go with it as a 46, which will be when it hit the road
Bill