Thanks Curt - I think I'll keep the non syncro 4 speed. My '48 advance design 4 speed shifts like a dream compared to the '39 4 non syncro but I like the challenge of hitting the gears with a smooth double clutch. I used to drive semis in the 60's and my first rig was a B-61 Mack tractor which required shifting a 5 speed gear box and a 2 speed axle at the same time. It took some time to master; if you missed a gear on a hill you had to start over. Once I mastered the trans it was a plesasure to drive. Thats what I like about the '39. (and the old lady never asks to borrow you're truck)