As an amp tech, I work on both of these amps. The '65 is superior to the '68. The '68 lacks high end, and is too bassy. Reworking the tone circuits, reducing the signal capacitor values to allow less bottom end, and changing the speaker to the Eminence Alessandro 10 improves a lot. Take the '65 instead. Even put the Alessandro into it, makes a big difference. Another mod for both is make the baffle hthinner and allow it to float properly, remove the 2 bottom brackets and make the baffle no thicker that 1/2". Seems like a lot of work, but it is worth making the amp more "airy".