To AJ,Slantsix.org has a great article titled 4 speed transmissions.I am no ace mechanic,just a DIY enthusiasts.With an overdrive 833,in 4th gear your input and output shafts aren't locked together by a sliding collar to make them direct drive,1 to 1,like in a non OD 833 (they are locked together in 3rd,though,in a 833 OD)There is a countershaft taking load between the two,therefore possible more noise,and possible wear.That is what I was asking other members about.That is because 3rd is 4th,and 4th is 3rd,in an OD 833.The lever arm is upside down on 3rd and 4th to fool the transmission.Chysler altered the gear ratio in the new" 3rd gear" (which is 4th gear when you shift) to get better gas mileage in the late 70s.So in an OD 833,1st,2nd,and 4th gears as you shift in your seat are operating off of the countershaft,no big deal for 1st and 2nd,but for 4th,when driving at 75mph for hours at a time,this could cause problems.
