see for example, the first photo posted in eBay auction #320971419969

That is a 100mm lens and the aperture scale is similar but, not quite the same...perhaps, the shutter you have originally came with a 135mm Sironar?

disclaimer: not my eBay auction...and not that of anybody I know nor is the seller anybody that I have dealt with in the past. I have absolutely no connection to the seller nor any interest in the sale.