I would post some pictures, but you already have them. I got
this one off gun broker about 10 years ago.
The square butt gun was originally a 4" i believe. Can't put my
hands on the factory letter as i write this. Usually you can tell if the barrel was switched out. the frame on a 2.5 is straight across the top and longer barrels have a slight drop before the barrel.
If i get a chance. i'll take some better pictures.