gumby-My 3600 has the original 4 speed trans. I think the T5 is fine in a half ton, the truck being much lighter weight, that's whats in my 46. Also the 3600 has the two piece driveline to deal with. My 3600 is mostly used around town so the taller rear end gears are much nicer than the 4:56s around town and I can do ok on the highway if needed.
