Well said in this one and the one above.I have no reason to doubt that what you have sounds great, just as you say, JeffI'm sure it's true for Marshall and Chuck as well.
This was the "Norlin" era at Gibson and the mid '70s wasn't always considered the "high point" of U.S. manufacturing.
Poor manufacturing in the 70s seems to have been a common problem for many sectors in the US. Came back to bite many/most of them as well. Many Fenders were pretty sloppy back then as well. I have one ('71 J) but from what I remember back then I was shocked that people in recent years were highly valuing Fenders from the 70s as much as they were. Heck, I'd go as far to say some near junk. But now they are "vintage." Not that there were not some good basses. I just never personally got the fascination with 70s Fenders. (No shade intended on those who have them and love them.)
