Your going to have to let the metal be your guide since the main pieces were typically uncoated and unpainted. Yes different years and even models (examples would be 68 where 390 C6 tailshaft housings were aluminum while the CJ C6 has a cast steel housing) Sorry don't have any pictures that cover that detail in 71-3
Here is what the FMX looks like that I did for the 69 Shelby I did a few years back
Bellhousing and tailshaft housing were finished as bare metal with a few stained area blended in lightly with paint so you could not tell. Main cast steel body was coated thinly with the ceramic natural paint a number of others have used for years on case iron four speeds. Its a little shinny from being fresh and under bright shop lights. Not noticeable and dies down once under the car and installed
Bare steel spacer between the main case and the tailshaft housing , some hardened attaching bolts, zinc speedo cable retainer with dichromated retaining bolt...