the "Special Information Catalog" is proof enough that GM never put the 283 in 57 light trucks as an "RPO", and no doubt the main reason for that is 57 was the transition from 265 to 283 and they wanted to get rid of the 265's on hand!!
but back then "if they were asked for" meant "the customer gets what the customer wants", unlike today where the customer gets what the dealer can find already built, if the dealer bothers to look - ANY customer request was a possibility in 57, like the odd side windows and 'school bus yellow' paint on my
57 panel , special ordered new for use as a logging camp ambulance .... too bad they were satisfied with the 235
Bill
