D6-9u

I recently purchased a parts catelouge for a D6-9u
Inside the front cover are the s/n's written in pencil and the date of 11-15-48
first one I think is written Diller 9u1892 and the second one is written Mot 9u5814.
No Idea what Diller and Mot mean??????
I'm betting this book came with these tractors.
It's a very long shot, but I thought if somebody actually had one of these tractors, it would be a nice addition to their collection. 😄