Hi I'm new to the site. Looks like I can get some good info here. I am converting the stock 3 speed to a 4 speed (sm420). I have a 49 3100 with the torque tube which I want to keep. I noticed that the size of the output shaft on the 3 speed is 1' and the 4 speed is 1-3/8'. Is there a tranny side u-joint yoke that adapts to the torque tube side? I would very much appriciate any info on this.
One of the reasons that the "bell" on the end of the SM420s is hard to find is that they tended to break from the torque reaction of compound low or reverse. On the 3/4 tons I've seen, the drive line is a hybrid: enclosed from transmission to carrier bearing mounted to a cross member and open from there back. These didn't break the end housing.
In my younger days, these pickups were still in common use and the country half tons were often used far beyond their intended limits. Most of the town or city half tons were probably three speeds and the country half tons were mostly four speeds. A friend of mine back in the day used his 51 half-ton for hauling water when the well went dry - a 325 gal oil tank, hopefully never used for heating oil. He did that till the frame cracked. After that, we used my 1-ton with the same tank. I was sharing a farm house with him.
He got the frame welded up and that winter, hauling firewood out of the woods with chains on, he cracked the bell on the back of the transmission.
1951 3800 1-ton "Earning its keep from the get-go" In the DITY Gallery 1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
