Bus driving Gearbox/ Licence question?

[Crazy Dazz]

My wife is looking at jobs where the ability to drive a truck or bus is an advantage.

Driving a bus as part of your job requires an F endorsement, which is easy enough. It is simply added to whatever class of licence you have. But that is the tricky part.
The licences are Light, Medium, and Heavy. And can have either an A (automatic) or B (synchromesh) restriction, or be unrestricted (ie a non-synchro "road-ranger" or similar gearbox.

Most of the trucks in question are just for delivering parts, carrying gear, etc. They would almost always fall within the Medium (or even Light) category, and I haven't heard of any not having synchro (in the last 30 years anyway.)

So my question relates mostly to buses.
MR will cover any bus, except a triple axle. I remember the old interstate coaches used to have dual rear axles. Are there still many buses around like that?

From what I have seen on site, usually the Coaster size buses will be manual (synchro) and the bigger buses are auto.
Again, I know that some of the OLD coaches were non-synchro, but are they still around?

So an MR-B would appear to be adequate for most.
But a triple axle requires a HR, and a non-synchro requires it to be unrestricted.

There is a big difference in cost between these, not to mention the size of the vehicle actually used for testing, and trying to get her to learn a crash box.