Those old Crown Coach school buses had non-synchro gear boxes. You had to match revs for the gear you were shifting into. You were supposed to double clutch the shifts but with a little experience you could "float the gears" and shift smoothly without using the clutch. Eventually you could match revs on shifts purely by sound without referencing the tachometer.
One time while I was learning to drive one of these things the instructor was halfway back laying across the seats as I drove. I blew a shift and got lost in the gears. The instructor, while still laying down calmly asked me what my speed was, then told me to rev the engine slowly increasing rpm. At a certain point he said for me to put it in 3rd gear and son of a gun the gear shift went in the 3rd hole as smooth as a baby's butt.
Here is the kind of bus I am talking about. They were manufactured in Los Angeles and used almost exclusively by school districts on the west coast. The engine is a big in line 6 laying on its side bolted to the underside of the bus. Made for a nice low CG and good handling by the standards of buses.
