I have a very nice 32S-3 75S-3 Collins Station. Superb old Swiss Watch. With incredible mechanical CW filter. And of course a couple of generators just in case.
I even built a home brew PLL synthesizer for it that gave me general coverage. I used it on my Navy MARS frequencies. Operated under that call from 1976-1995.
Dropped out in 1995 when we moved back to TX from OK. Not sure what year they eliminated MARS altogether.
Yup, some of the old Collins gear had great CW filers.
I love selectable narrow filters...they are a must for QRP. I love QRP :-)
I got the old GRC 9 rigs for 70 dollars each...got the ones marked USED/REPAIRABLE as they are easy to work on. They are quite expensive nowadays.