| Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | SM420 is the 4-speed GM started putting in trucks in 1948 and used through 1967. It might be the one in your '39 but only if someone has performed a swap.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble... | 
