an od can be built as stout as the regular one to one four speed with a cast iron case or bushing in the aluminum.
Bigger difference comes in the gear shift width.
The od uses the last gear so the wheels are turning faster than the driveline which saves fuel.
So with that, the OD has a wider gear ratio range with only 3 gears....basically its a three speed with an overdrive last gear.
So that being said, you will notice that if you "get on it" you will have to rev the engine more and hold a gear longer to keep the pull going and it will have a slight hesitation when you get into the new gear.
Not so much a negative but if you go with an OD, don't plan on any competitive situation because it will make a big difference and in extreme competition (track) it will disappoint.
But as a gas sipper .....perfect.....interstate highway, low RPMs, low noise. 70+MPH...... nice.
