Ed,
Have a look at the alternator in this article. I have one that I plan to put on my OC-3 and I'm sure it would fit under the side panels if you make the correct brackets for the 77.

[url=http&#58;//www&#46;cletrac&#46;org/newbb/viewtopic&#46;php?f=21&amp;t=2227:32sh18ja]Alternator conversion.[/url:32sh18ja]