Lee, that is a sizable project replacing all of those RCA jacks with 3501's, but probably worth it. Obviosly you've done a lot of work on the board too. I was at a surplus shop in San Jose in the late 90's and found a stash of the original RCA jacks. I bought a pile of them and only have a few left. It looks like you used the fiber shoulder washers on the 3501's which is the right thing to do. Is there not a better solution to the 4739?