[Nova Research Project]

69gmmuscleluver,

These superseded and replace each other many times. In the 70 Nova AIM there were several #'s just used during production.

From purely a part number point of view:

3991430 fits 71-78 Camaro 8 Cylinder with Air conditioning. Replaced 3991429 and 3946804 and 4939900 and 3686113 and 3997781 and 3973397 and 4950200

3991429 fit:

71 Camaro (SP HIPO), Pass Nova Monte Carlo Camaro w Air Conditioning
71 Pass Monte Carlo 454

3946804 fit

69 Camaro 302, Chevelle (SP HIPO) 396

4939900 fit

69 Chevelle, Nova V8 with Air Cond, Camaro with Air Cond, Fan Drive (not 396)

I ran out of steam looking these up and did not want to dig out more books. Looks like 69 up V9 with Air Conditioning.
3686113, 3997781, 3973397, 4950200 were probably the Assembly line parts.

I hope this helps,
Greg