When doing replacement or upgrading on 1960 – 1966 GMC 1000 1500 2500 3000 3500 Series 2 4 headlamps with, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight 1966 H5006
High Beam Headlight 1966 H5001
Brake 1966 1034
Dome Light 1966 211-2
Front Turn Signal 1966 1156
Parking Light 1966 67
Rear Turn Signal 1966 1156
Tail Light 1966 1157
Low Beam Headlight 1960 – 1965 H5006
High Beam Headlight 1960 – 1965 H5001
Brake 1960 – 1965 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
High Beam and Low Beam Headlight 1960 – 1965 6014
Brake 1960 – 1964 1034
1965 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
Low Beam Headlight 1966 H5006
High Beam Headlight 1966 H5001
Brake 1966 1157
Dome Light 1966 211-2
Front Turn Signal 1966 1156
Parking Light 1966 67
Rear Turn Signal 1966 1156
Tail Light 1966 1157
Low Beam Headlight 1960 – 1965 H5006
High Beam Headlight 1960 – 1965 H5001
Brake 1961, 1965 1034
1960, 1962 – 1964 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
High Beam and Low Beam Headlight 1960 – 1965 6014
Brake 1961, 1964 – 1965 1034
1960, 1962 – 1963 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
Low Beam Headlight 1966 H5006
High Beam Headlight 1966 H5001
Brake 1966 1034
Dome Light 1966 211-2
Front Turn Signal 1966 1156
Parking Light 1966 67
Rear Turn Signal 1966 1156
Tail Light 1966 1157
Low Beam Headlight 1960 – 1965 H5006
High Beam Headlight 1960 – 1965 H5001
Brake 1960, 1962 1034
1961, 1963 – 1965 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
High Beam and Low Beam Headlight 1960 – 1965 6014
Brake 1960 – 1962, 1965 1034
1963 – 1964 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
Low Beam Headlight 1966 H5006
High Beam Headlight 1966 H5001
Brake 1966 1157
Dome Light 1966 211-2
Front Turn Signal 1966 1156
Parking Light 1966 67
Rear Turn Signal 1966 1156
Tail Light 1966 1157
Low Beam Headlight 1960 – 1965 H5006
High Beam Headlight 1960 – 1965 H5001
Brake 1960 1034
1961 – 1965 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
High Beam and Low Beam Headlight 1960 – 1965 6014
Brake 1960 – 1962, 1964 1034
1963, 1965 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
Low Beam Headlight 1966 H5006
High Beam Headlight 1966 H5001
Brake 1966 1034
Dome Light 1966 211-2
Front Turn Signal 1966 1156
Parking Light 1966 67
Rear Turn Signal 1966 1156
Tail Light 1966 1157
Low Beam Headlight 1960 – 1965 H5006
High Beam Headlight 1960 – 1965 H5001
Brake 1960 – 1965 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157
High Beam and Low Beam Headlight 1960 – 1965 6014
Brake 1961 – 1963 1034
1960, 1964 – 1965 1157
Dome Light 1960 – 1965 211-2
Parking Light 1960 – 1965 67
Tail Light 1960 – 1965 1157