I'd have two questions: when were arch bar trucks banned from interchange in the US . . .
and Mind-Like-A-Steel-Trap Thompson wrote:
I've finally memorized this one, since we cover it every six months or so: 1941.
And I tracked down the AAR Field Guides to Interchange Rules for 1941 and 1942, and after several deferments the final date was August 1941.
I doublechecked my books, and the August 1, 1941 date is in Supplement #1 to the 1941 Field Guide which was effective July 1, 1941. Supplement #1 was a separate booklet that was stuck inside my copy of the 1941 book.
The 1942 book flatly states archbar trucks were banned in interchange, so there were no further deferments.
