[mssl72]

I found it listed in the '60-'64 Chevy By Numbers. Alan shows it listed for 1960 and 1961 Corvette, 283/245hp and 270hp. He even has a picture of it pointing out it has no vacuum advance and is dual point. I looked it up in my parts book (dated May 1, 1966) and here's what I found in there:

56-57 PASS.w/dual 4BC
57 Corvette (exc. F.I., H.D. Dist.)
58-61 Corvette w/dual 4BC, H Per............w/dual points....... 1 ........ 35.77

I'll bet you can't find a new one now for that price!
I came up with the same date as John Brown. I guess it was probably a service replacement unit.
Hope this helps.