In a Chrysler (or Ford) overdriven 4 speed, what becomes 3rd gear was the old 4th. All they did was turn the shift lever on the trans upside down so that the GEARBOX shifts 1-2-4-3 as YOU shift 1-2-3-4 and of course "regeared" the original 3rd gear
Fourth or "high" gear in a normal, traditional 3 or 4 speed is always a straight through shaft coupling and cannot be changed. You could throw away the cluster gear and 4th gear would still work
