A lot of changes happening in this period. From the the new OBEL and first steady use of effects other then a wah in his arsenal, to the reintroduction of Wolf. Then Wolf gets the blaster put in once the OBEL gets an in/out switch which requires the db's to be raised for matched levels on both sides of the switch. Then he actually puts humbuckers in Wolf. Like the changes to Alligator in an attempt to find what he actually wanted out of a guitar, this period represents what he actually wanted from the effects side of things and culminates in Aug of 1979 with the introduction of Tiger, new buffer preamp and the new Cutler effects rack and switching system. The pickups get switched out, an occasional effect gets swapped out and a different power amp may be utilized for a brief period, but this Tiger/80's rack stays a constant for the next 11 years. And then it pretty much stays the same with only an addition of the midi system which was it's own rig in parallel with it. I agree that 77/78 were pretty big years on the equipment front for Jerry.
Disclaimer: I make and sell Buffers. I also sometimes Modify, Build and sell preamps and amplifiers. My opinions are not intended to be sales pitches. I am a one man shop and prefer to spend time with my wife and family, i work full time on call and love to spend my spare time doing other things. I only make, modify or build things for those that seek them.