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| | | | Joined: Sep 2007 Posts: 2,644 Shop Shark | | Shop Shark Joined: Sep 2007 Posts: 2,644 | I don't know much about your transmission but I can tell you it's successor, the SM420 is a rock crusher; in production for 20 years, military for 10 more; used in 1-ton trucks and busses; today's hot setup for rock crawling because of low gear.
I recently had a 3.55 R&P installed in my 1/2 ton and the SM420 takes on an entirely new persona. With the taller gear she still pulls away smartly in second gear with an equal gear change from 2 to 3 and 3 to 4. The syncro second is like driving a full-syncro 3-speed and second is tall enough to make it a useable downshift. If you like to put your truck to work it's nice to know you have that low low gear for dealing with heavy loads and/or steep terrain... plenty of pull without the instant red-line you get with the 4.11.
I'm really glad I decided to keep mine so if yours is the forerunner of the SM420 you have a sturdy transmission, and I hope someone comes along with more in-depth info on it. | | |
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