My father could float shift (no clutch other than takeoff) a model a..he drove truck back in the thirties and forties,when spur gear transmissions were common.Timing it is the same as double clutching,missing the shift can be deadly to the transmission.As a kid I was in awe of that,for the life of me i couldnt do it..I try it now every once in awhile in his memory..and yes I have a few spare transmissions just in case...