Suppose I should clarify that. Depends on what transmission you have. The TH400 (3-speed) had a ratchet type shifter. If you put the shifter down in low, then you can push the shifter handle to the right and it will upshift only one gear at a time. If i'm remembering right (which is questionable lately) the 3-speed trannys weren't available until 69. If you got a 2-speed you're out of luck.

I'll look if I have a pic of the top of the shifter.
here's a pic of the top.