Have arguement with dad. He says that the 95 GMC 3500 had a "true 5spd" (5th gear 1:1). I think it was an overdrive. NV 4500? We don't have it anymore though.

What did that model of pickup come with for a five speed trans?

our 94 5 speed had a 1:1 4th and an overdrive 5th. (454 also)

That Would fit the characteristics of an NV 4500. It's an OD trans.