The spread between the granny first and second in an SM420 is big enough that I would not want to drive it that way all the time. You would be in first just a few feet and then shifting again, and then again to third real soon.
The spreads between second, third and fourth aren't great anyway (see Patrick's comparison to the Saginaw 4-speed) but the jump from first to second is much worse than any of the others.
Let me say again, that with a GMC 270 (sligthly larger than the Chevy sixes) my truck drives nicely with an SM420 and 3.08 gears.
I won't win any drag races, and the few times I've used it to pull a trailer it was very disappointing compared to my big block powered 1-ton, but running around town and light highway commuting it really is quite workable.
I'd forgotten about Patrick's shifter. It really is a good idea because it puts the shifter back near the stock location.
