Originally Posted by crenwelge
I found 1st and 2nd rather awkward. In fact we had 2 1st gear hills around here and I would almost stop before I approached the hill because I knew I couldn't go from 2nd to 1st fast enough.

However, the real advantage of the transmission is demonstrated in the chart pvfjr posted.

https://photos.google.com/share/AF1...RXBXV2NDMFVFUlltTkVFaGVaM0VBMWxONC1ucU1n

It shows 62.2 as top speed with the low option axle and 69.1 as top speed at 3000 RPM with a 6 cylinder. My GMC 550 had a 370 which was actually a 371 Olds. I shifted up at 4200 and shifted down at 3800. I ran 10.00x20 tires that did about 500 revs per mile. Put the speed calculator to that. And then I hear all these stories that these trucks were meant to go 45 MPH.
Unfortunately, I made that chart when I was pipe-dreaming about finding a NP540-GO when I was assuming that I had an SM420. Odds are good that if I already have a NP540, it'll be the -GL version with a 1:1 fifth in it. But, it'll have a much better gear spread, so I'll take what I can get.

--Paul
1955.2 Chevy 6400 Dump Album