Have to sell. Is it rare?

[WorkinLonghorn]

Hi there. After owning this truck since 1996, purchased from the estate of the original owner, I need to sell it (knee issues). I'm working on what to say in the listing and don't want to overstate what it is. Is a New Process close ratio 4spd. considered "rare"? I sure don't see or hear about them ever. Is a "Longhorn" (8 1/2 Ft. bed) considered "rare" or just very uncommon.
I'm not sure if I'm up-to-date on my dues here so not sure if I can ask a "what's it worth" question without being shot but I really have no clue at all. It has a new high quality clutch and a GM crate 350 Ci. with about 5K on it.
Anyway long story short, can I say "rare NP 435 transmission" and "rare longhorn-style bed"? How about "rare factory tach dash"?
It's worth a lot more to me than the market will bear I'm sure, but I still don't know where to start or how to list it. Thanks, Brian