I am faced with the same dilemma of OD versus non OD, but my car has a 2.xx:1 differential ratio, 13" tires, and a 273 V8. Since I have all the parts, I will install the non-OD 833 first instead of the OEM 3 speed. If I am not satisfied with the 833, then I will install the 833OD.
In terms of engine rpm, going 70 mph on the highway was about 2,000 rpm in my Honda recently; nice and relaxed. I intend to do more highway driving in the Dart than local roads, but I still want the car to be able to move with some gutso on my way to the highway.
