1983 marked the final year of the F-100, making the F-150 the lightest pickup available on the market. F-100s and F-150s were virtually identical with the exception of smaller brakes and a 5x4. 5 bolt pattern on the F-100 axles, as opposed to 5x5. 5 on the F-150. F-100s over a certain GVWR and / or without power brakes did use the F-150 axles. Also, the 1980 -- 1983 F-100 was never offered with four-wheel-drive.

Answer this question based on the passage: when did ford switch from f100 to f150? Let's have some stream of consciousness first.
This is the relevant information: 1983 marked the final year of the F-100, making the F-150 the lightest pickup available on the market. So, the answer is 1983.