HH,
The 322 Buick engine was only available in the 10,000 series (2-1/2 ton) trucks in 56 and 57. No other engine was available in these truck with the only option being the 4-barrel carb. It's shown on paper as also being available in 58, but I've never seen a '58 with the 322. I believe Chevrolet covered their bases by listing both the 322 and 348 for 1958 just incase there was a problem with the ALL NEW 348 production.
Tube type tires seem to be way more common than the "standard" tubeless tires (at least around here). I've owned many 56 & 57 1-1/2 and 2 ton trucks and have only had one with tubeless tires the rest all had the 2-piece 20's. I can't believe these trucks were all refitted by the owner/dealer, they must have come from the factory this way. That said, I don't have any info showing tube type tires as being optional.
Mike B
