not sure why anyone would have to point out something like the sender being built so it can't be put in the wrong way without modification, and I doubt there's anything said in the manual about it - the year appropriate manuals are quite good, if you have some understanding of vintage vehicles and mechanics, but they weren't really written for owners who didn't have any familiarity with the company and the machine
you couldn't find a 52 manual because there isn't one, there's a
48-51` manual and a 52 supplement that covers the changes for 52, both available from most vendors, along with the assembly manual
Bill