Just guessing, but probably both plates install on the outside. The one closest to the backing plate is probably just there to seal the back side, assuming it fits flat against the backing plate. The cables for 3100's are similar, and both plates go on the outside of the backing plate with a thick felt gasket to seal them.

Like Dan said, a picture is worth 1000 words.


Kevin
1951 Chevy 3100 work truck
Follow this saga in Project Journal
Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.