Just picked up my two model 64s this afternoon that I ordered from Centerfire. One was a 64-5 and the other a 64-6. The 64-5 has the barrel marked .38 S&W SPL. +P and is stamped Indiana State Police on the RH side. I didn't notice it when I picked it up as I thought it was the S&W logo and the Pachmayr grip covered some of it. I removed the grips and there is also a series of letters and numbers inscribed on the LH grip frame ASP 10006. It is also a round butt. Interesting!
Sorry about the crummy lines in the photos..I think my 15 year old Casio camera may finally be dying..

