Slant 6 engine decoding

Hello Everybody,
I hope someone can help fill in the missing pieces for me. I have been through what seems like a million pages decoding my block. Got most of it but I am stuck on the final numbers. Please correct me if am wrong but this is what I have so far.
PT 225 R 2450949. PT = Trenton plant, 225 self explanatory, R = Passenger car, 2450949 from what I can tell should be build dates but makes no sense to me.
The number on the block as per the picture is a casting number that dates it to 1968.
Appreciate any advice you may have.
Ron
engine 1.jpg engine 2.jpg