There are several variations in Chevrolet T-3 headlamps.

What does T-3 stand for? The "T" stand for "tilt" and the "3" stands for 3-degrees. The headlamps were to be tilted 3-degrees down and 3-degrees to the right. The headlamps were produced by the Guide company in Indiana and the Guide company supplied numerous bulbs and lenses for GM.

See this YouTube guide to T3 headlamps.

1956 - "Sealed Power" lettering is larger than the 1957 year.
1957 - "Sealed Power" lettering is smaller than the 1956 year.
1958/1959 - Four headlamp configuration introduced. Plain triangle with T3 with "GUIDE" above the T3.
1960/1967 - Plain triangle with T3 with "GUIDE" at the bottom of the bulb.
1968/1970* - Triangle has small, vertical lines.
1971 - Return to a single headlamp with 1968/1970 marking.
1972 - Triangle was removed and T3 Guide moved to the bottom of the headlamp.

* This version was also used in 1971 full-size passenger cars with four headlamps.

° The 1960-1967 variation shown here has the word GUIDE moved to the bottom of the triangle and in rectangular, boxed area. The background of the triangle is clear with no lines.


° The 1968-1970 variation shown here is almost the same as the second (1960-1967) with the exception of the background of the triangle that has thin, vertical lines.

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