For what it's worth I will share this tidbit. I finally ordered a shop manual for my 55/1st 4400 from Chevy Duty. Along with the manual I also ordered the '55 supplement, thinking this was something I needed for the mid year model change. The supplement was $6.95 and consisted of 13 pages on the care and feeding of the 1/2 ton rear axle....sheessh, not what I expected!

Stuart.