O.d.
Ok home. I'll post a picture of the over drive and we can see the difference between the two. You can see that tiny little overdrive gear where third is supposed to be. There's not much different about the linkage then the 3rd 4th shifter ear up side down (or facing up instead of down like a 4 speed). First gear is lower for the economy slant 6 and 318. The overdrive gear is for economy on the freeway for a slant 6 and 318 car. First gear would be great and all for taking off, that second gear that has to take up so much room on 3rd and 2nd as in gearing. The overdrive gear it's so small week and not use so much good for a performance application.
LOL well when the clutch is released and the motor is on all the gears are moving all the time. That's why even when the car is in neutral and you release the clutch it still has a small pull on the motor because it's going to get all those gears moving - countershaft and 1st through 4th . Input shaft Is solid with 4th gear which always drives countershaft which always drives 1st through 3rd even when in 4th gear is connected to the output shaft the counter shaft and all the other gears are still turning. It really boils down to which gear is connected to the output shaft. I'll get into reverse for my advanced class LOL
View attachment 20160329_202539.jpg