Now that that's cleared up, let's deal with it. The right floor panel is my current focus. The seat rail was where I started, and ordered a new right inner, right center and right outer seat rail from Robin at alfaparts.net. The parts look great, but don't fit to my current floor. The pictures below are the current state - you can see my attempt at a patch panel in the center of the rear panel. Not too shabby for my first welding job.
Right full floor by SuperBee16, on Flickr
Right rear floor by SuperBee16, on Flickr
The inner rail I ordered would work just fine (replacement shown in front of current rail still in-place)
Right inner rail by SuperBee16, on Flickr
but the floor below the outer rail on my car seems to dip lower along the edge AND also dips down in the center. There's about 3cm between the floor and the replacement rail.
Right outer rail by SuperBee16, on Flickr
I've since decided that the rust situation will be easier to replace the whole floor than to try to patch. Robin says the floor panels he sells will work to replace mine (and will obviously match up to the seat rails I've already purchased from him), but I wanted to check with you all first on a couple of things.
Several vendors (who actually have images of the items they are selling) show two types of floor panel portions for the rear - neither of which really look like mine -
with facets, 
or flat. Depending on the vendor, both panels say they fit all years 68-85, and some specify the individual years that it will fit (including a 1974).
So, here's my questions for you all
- Do the faceted panels for sale out there have different heights on the exterior edges?
- Which vehicles do the different types of rear panels actually go on?
- I understand 1974 was kind of an awkward teenage year - is this odd floor shape on mine a 1974 thing?
- Some vendors show the flat panel for the right, and the faceted panel for the left - bu not all do. Does it matter?
Thank you all for the help!
