FYI:
the only difference between 1970 & 1971/early-1972 are the drivers side "male" parts;
1970 it was a retracting belt, while the other was a fixed length in a plastic sleeve.
I believe that the following belts all have unique lengths:
- 70-72* front "female" belts (same length for shoulder and lap belts)
- 70-72* front "male" shoulder belts
- 70-72* rear "female" belts
- 70-72* rear "male" belts
Now I have never seen them in person, but I have understood that the optional rear shoulder belts may have been the same as the front shoulder belts - I do not know if the "female" end of rear shoulder belt was the same as the front or rear "female" belt.