There are times when you can just step on the clutch and just haul her down in low without any clash or crash even with a non-synchro low. If memory serves (or swerves) I think its when the govenor kicks it into the freewhweeling mode, usually below 30 mph (if the governor is wired into the circuit). So while an all synchro is nice, it is not require for slipping back into low while still rolling..
Now, as an aside, an advantage of the crashbox is that it can be fitted with a 2.94, a 2.54(?), or a Corvette 2.20 low gearsets- just need a matching cluster, second gear and the main(?) gears (the one with the clutch spline on it). Its just an easy swapping of parts within the stock case, be it "55-'64 pass, vettes, pickups, and '62-'64 chevy twices (case length makes no diff). It may be easier to find an o/d to fit this tranny than the more rare Saginaw o/d
I personally rode in an early '40 sedan w/ 278 incher, mellings lopeing cam and full 'vette carb/exhaust setup. It was a good daily driver with a 2.20 low crash box (oh yeah and a 4.11 rear gear), with the 4.11 it would soar past 40 mph in low! The owner had installed this gearset into a 40 ish pickup (floor shift) tranny and was still using his stock 4.11 torque rear end- the later model tail shaft had to be used and machined to suit the torque tube settup both for length and matchup to the single splitable u-joint used on these torque rears. This was a really clever setup.
