transmission gear oil on 1992 Chevrolet 1500 Pickup

what weight and how much gear oil does the 5 speed transmission take.

There are 2 different 5 speed manual transmissions available for your truck and each takes a different fluid. Capacities are listed below

5 Speed 85mm & 109 mm 3.6 pt (US)
New Venture Gear 4500 8 pt (US)