The bodies left the Ghia plant incomplete in various steps. The distributor bought 5 (or so at a time) There are no major telltale signs. We had assumed: floor ebrake handle, coin tray, Becker radio, Citroen roof antenna and late dash configuration. For sure only the Germany cars had floor mounted ebrake handles, did they all have them is another research project.
These cars evolved thru production and many things changed. It is hard to identify when (if logical) items were upgraded ( rear fender gussets, 1 or 2 piece seat, rear defrost, dash configuration [there are 3], rear rim width [ 7.5 vs 8in] , magnesium or aluminium rims, Ferrero variation on steering [all leather or all wood, or dished], different spare tire hold down, very early cars have steel wings and hood, very early cars have 289s.
Unfortunately as we have seen the paperwork go trashed when the scrapped the filing cabinets and no true 'Marty' style reference exists.