It simply became impossible to tune my 1968 Gibson Acoustic properly without breaking my fingers of my left hand. I assume the original Kluson Deluxe were worn out and getting way too old, as even my electric string winder started to complain. I replaced them with these Gibson tuners and they were a perfect fit. The replacement was done well under 30 minutes without any modifications needed. I am pleased with the quality and in my case with the looks. Thanks to the Thomas team to make sure I picked the right model tuners for my specific guitar