Cars with the electric seat back locks still have the manual release knob. Otherwise you couldn't move the seat forward if there was a release failure or dead battery.
The manual release was located on the backside of the seat, though, just above the latch, where the solenoid would be located. At least that is how it was in '73.
My seat looks just like the one Phil posted. The Riv's seat doesn't have the knob, but it does have a manual release behind the seat liek Zach said. But we're talking a 3 year difference.
