Rugo,
You are correct in what you are describing. I just did mine (1951 3100),.but mine only had the hole on one end, not both ends. I studied it after I had installed everything, and it did not appear that the roller would run out the end of the track, whether the window was all the way up, or all the way down. It might, but it didn't appear so. I put in a new rubber bumper/stop for piece of mind.
Mike
