Anyone familiar with the different ribbon tweeters Brian may have used in the STIIIs? Mine appear to have Pioneer ART-54Fs which does not seem to be the norm. Most seem to have JVC HSW1101-01A. I got these speakers from my grandfather, who purchased them new from a now defunct shop out of South Carolina. He was not one to modify his own stuff, and he had records for all of his audio equipment so I’d imagine if he had someone swap them he’d have some record of it… but maybe not…