I've seen several open top 73's in the past, but I've never owned one. I did have a very high condition open top '76 in my collection at one time. I believe the serial number was 5425. A friend of mine did have a '73 open top at our show here this past week-end. It was the only round barrel '73 open top known to exist and the condition was nearly new. Almost 95% of the original bright blue, with 80% bright case color on hammer, lever and even traces on the butt plate. One of the best 73's I've ever see.
Buck