AC carbs had hot idle compensators. Not sure if jets and rods, idle feed restrictions are the different between manual and auto, all have the same size throttle, ventura (340-383 one size, 440 bigger). I picked up a few more and I have a 69 383 manual and auto carb, I'll check for differences. One thing I found different, 68 383 stick has holes in the primary blades and the 69 doesn't. Looks stock, not buggered up.