They are not a "non synchro tranny." A "non synchro tranny" or "crash box" or "spur gear" before the advent of special "slick shift" or "face plated" race boxes was such things as the old Ford gearboxes. They were straight cut gears, "spur gears" and none of the gears was synchronized. Even today, some heavy truck boxes are such. In this case you had to learn to double clutch and match speed/ RPM between gears so they would mesh up or down, with little "crash."
The older 2 speeds, Mopar or GM / what, what we are referring to here, were not synchro into FIRST. But usually, you only shift into first (mostly) when stopped. I did, and anyone can, learn to "double clutch" into 1st at a roll, such as when approaching a stop sign
