Colt Trooper Mark 3 357

[Another old Jarhead]

I have a question about the Mark 3 if anyone is willing and able to answer it for me. When I was 16 ('79) my father let me buy my first gun from him (yep, made me pay for it), although he kept it until I was out of the Corps. It was the .357 6" Mark 3 and I fell in love with it when we went shooting when I was 12. Anyhow, I still have the gun with no intention of getting rid of it but I was curious as to when it was made. I looked up the serial number on Colts website and the 5 digit serial number (2***4) would lead me to believe that it was 1961. But the Mark 3 didn't come out until '68 or '69 I believe. There is a Capital "U" after the 5 numbers but, after some internet searching, I believe that this may be the inspectors mark. I called Colt's customer service and was told the they didn't have lettering until the early 80's. Very confusing to me and I can't seem to find the correct answer. Sadly my father passed a couple years back and was going through Dementia prior to that, so I couldn't ask him. I figure that, when I go, I'll let my son have it. Appreciate any help.

Think I have it figured out. The revolver I have from my father was made in 1981, according to something I found while searching, the year I went into the Marine Corps. My memory of being 16 must be mistaken and it was when I was 18 instead. The .357 I shot when I was 12 had to have been another one. Pop had quite a few guns so that makes sense to me. Regardless, he still let me buy my first gun from him and I still have it. That alone makes it all good to me. Some things just can't be replaced.