Matt, I have a 63' Heavy Duty Econoline with a 66' - 200cid engine and the 3.03 manual 3-speed trans. The stock rear end in my H.D. Van "was" a 4:11 ratio; and that was geared a little too low for me. I always worried someone was going to rear end me when going out from a signal because I was having to shift about half way through the interesection. It also made it difficult on the freeway, because it felt like the engine was wound tight when doing about 50-55mph. I installed a 3:50 quite a few years ago and it is a lot better; but it still feels like the engine is wound a little tight when pushing 60-65mph. These first generation vans were not really built with high speeds in mind, as you are probably well aware of. Personally, I would think about swapping in a 3:25 or possibly a 3:00. I am pretty sure some econo vans have gone to the 3:00, but do not take my word for it! I believe that below 3:00 is not so good, again you may want to talk with some experts on this! Good to see another Econoline on the Fordsix website. Good Luck! Jim
