I just got a 68, drip edge, the chassis is stamped 1967. I am in love with this amp, the bass channel is fat, lush and has a ton of beautiful grind. Simply stunned by how good this head sounds. Fat with great clarity. I have a Garnet head that sounds quite similiar as well. I wired my cab with a DPDT switch, so I can switch between 4 and 16 ohms for my various amps. Having a few cabs, I tried the amp at 4,8 and 16 ohm, for my tastes, the 4 ohm match really sits perfectly with the amp. I know some folks run them into 16 ohm, but the advice I was given was to not have that much of an ohm mismatch, with an amp built for 4 ohms. 8 ohm should not be an issue. Still an absurd bargain IMO. Hand wired amps with major mojo for 400.00 or so, the early Silver Face amps will likely be fetching a lot more in the coming years.