Take a look at this picture of the longer seat back rails from the 1978/79 era planes.  It is important is all our seats to correctly assembly the various parts, but in these, it is very critical , since placing the spacers in the wrong place causes an angle change, which over the longer length, gets bigger.  These had the spacer on the outside near the bolt, not between the rail and the seat.  It wore the metal down, there is a channel it cut (alum dust in carpet, etc).  They also got bent and abused in various other ways.  The upholstery was great though!

That is why  our planes must be assembled in the correct order or parts like these get ruined.

Enjoy!

Roscoe
Yankee-Aviation.com
513-519-7008