Researching an old Conn Trombone

[opus37]

I have run across an old Conn Trombone. The serial number is 6542 and it has "Prime of Elkhart" on the bell. The case is a top loader which looks in great condition. The horn has a a couple of small dings in the bell and near the counter weight area. By the way, counter weight is outside the tubing. There is markings that suggest it is a low tuned instrument. Does anyone here have information about such a horn and it's possible worth?