Hi Danny; by the pics provided above, it seems she lacks the lock bar rear sights assembly. Is it a T105E1 assembly?
Mmmmm... From the information available, the T105E1 assembly was approved between oct/nov 1944, but it is very unlikely that a wartime M1 has been issued with that kind of sights (accordingly, i.e., to B. Canfield's book); maybe some very late specimen, made around May/June 1945, could had the new sights installed, but there's no evidences (pics or documents). I would rather tend to believe in a post war retrofitting; nothing bad, anyway, since finding a matching barrel/receiver is usually the hard job (not to mention the correct stock).
I guess some lock bar are available, if you want to uograde you rifle. Try on the web, or Numrich.