If you read the end of the article I posted above it says that the clocking on the pitman arms is different for the different models. Which would mean that using a C body or van box in an A with an A-body pitman could mean grinding a new master spline to re-clock the pitman arm.
I was curious about this. We’ll the box sold while I was trying to figure it out. All mopar show and it was the only manual box here. Not sure why these seem to be so hard to find outside of $100+ on eBay….