Back in the seventies when we still ran gasoline route trucks, we had quite a few AT540's running around. Some were C60's with the 350V8 and some were C65's with the 366V8, but they all used the same AT540 transmission. We even had a couple Ford LN750 trucks with the 361V8 and the AT540. They were very tough transmissions and held up very well. The drivers liked them much better than the manual transmissions. We also liked them because there was no clutch to worry about and they were much less likely to destroy driveshafts and axleshafts at the hands of inexperienced drivers.
Our route trucks are all diesel now, but we still use Allison transmissions. The smaller diesels use the AT545, which is just a disel version of the AT540. The heavier trucks used the MT643, and now we have quite a few of the Allison World Series electronics. I've been working on and with fleet trucks for almost 30 years, and I would recommend the Allison to anyone.
Hope yours works out great.
