So gentlemen, help me to understand the forward pattern (PRND21) automatic/manual valve body concept.

You can put the gearshift lever in the "D" position and the transmission will shift for you? Why buy/use it then (sounds like the functions of an automatic transmission)?

Or, you can shift it manually with the gearshift lever?

I thought that, with a manual valve body, whatever position you put the gearshift lever in was the gear you got (eg. position "1" = 1st gear, postion "2" = 2nd gear, and position "D" = 3rd gear)? Is there still a need for the kick-down linkage?

Please shed some light on the Black Magic Voodoo that is a transmission!