I agree with 2ton46, I am not looking at overdrive for more top end speed but to lower the RPM. I drove my 58 2-ton to church and back the last 4 days (20 miles each way, 17 of it on the freeway). 60mph is 3600 RPM, 70mph is 4200RPM. I sure would like to drop the RPM as it is a lot quieter down around 3,000 RPM. Quiet is good when you are on the way to run sound and want to hear something when you get there! LOL. If I get a bit better mileage, it won't hurt my feelings either.
