I don't believe you're gonna find autoformers on anything but the Mac's. That is a central part of their character. Really, the Mac transistor amps are somewhat textbook and basic and not all that wildly special or unique in their fundamental design, other than the use of autoformers. They were well engineered, well implemented designs, high power for their time, conservatively rated, robust in permanent installations, and quite clean in the sound, kind of a military spec mentality in a way. Their tube amps, on the other hand, had some ingenious/revolutionary ideas going on and they wound some very special design and high quality transformers to facilitate these design ideas.
All that said, the transistor Mac's do deliver the transistor era Jerry guitar sound as good as you're gonna get it. It's the real thing and there is definitely a warmth and bigness to their tone.
You can find autoformers out there and it would be cool to experiment with attaching these autoformers to other amplifiers' outputs and see what you get. Although it's not likely that these stand-alone autoformers will be wound with nearly the quality and performance of the Mac's.
Also, another idea worth pondering is that Jerry used the 2-ohm tap on the Mc2300. This tap also happens to be the point where the autoformer was connected. So basically, Jerry's speakers were wired directly to the output transistors and got the least autoformer interaction possible from that amp. Still, the fact that the autoformer was tied to the outputs surely had some effect, but we can tell that it was minimal by the nature of using the 2-ohm tap. So maybe there are some other amps that would do a good Jerry. But we also know he surely tried a lot of amps and always came back to the Mac. I strongly believe that the real test and the zone of use/abuse that kept Jerry coming back to that amp was in how it sounded and behaved when it was banged on and abused, driven to its power limits and forced to squish and distort a little. That's where clean power amplifiers show their true colors. Some will simply go to shit when abused, some will get harsh sounding, some will get unstable, some will sound wimpy, some will become fuzz boxes, some will fry, some will catch fire, but the Mac seemed to take it well enough and feel and sound good for guitar the way Jerry played it.
... and it's just like any other day that's ever been...