Hi all,
I think the SM420 was perfectly designed for its original purpose, use in the field. I spent hours walking behind our trucks in the alfalfa fields as a kid, throwing hay bales into the truck as Mom crept along in granny gear. It was the only gear we could use to start out with a load of durum wheat in a soft field with a small 235 or 292 6 cylinder. Not so useful or enjoyable to drive in traffic.
I don't need an overdrive; just better gear spacing. In fact, as Grigg noted, an OD might force me to swap back to the 3.90. A 0.75:1 OD with 3.38 gives an effective final drive ratio of 2.53, extremely high given I don't plan to go over 60-65 regardless.
Was hoping that a car type 4 speed such as a Muncie M20, B-W T10, etc... would be a "bolt in". If not, I will keep the original. Thanks again.
