5/8 Ton,
Once you get good with double clutching, you will be ready for the next step, which is shifting without using the clutch at all.
It is all about experience with your tranny and listing to the sound of the engine so you can match the gears. To shift up you might have to give the gas a little bump to get it out of gear, and to shift down you will want to rev the engine up once you are in neutral so as to match the speed to the lower gear.
I used to do it all time when I had a 3 speed transmission in my '51 1/2T. I had to remove the synchros because they were worn to the point where they would lock the tranny up in gear. So I got very practised at double clutching and shifting without using the clutch.
Kurt
