Can you use a ignition switch from 1984 Ford F-150 on 1983 F-150?

It's highly likely, but not guaranteed, that an ignition switch from a 1984 Ford F-150 will work on a 1983 F-150. Ford generally maintained design consistency across model years, especially for parts like ignition switches.

However, there's a small chance of incompatibility due to minor revisions or changes Ford might have introduced between those model years. Before installing it, it's best to:

* Compare part numbers: The most reliable method is to find the part number on both the old and new ignition switches. If the numbers match, they're interchangeable. You can usually find part numbers on the switch itself or in a parts catalog.

* Visually inspect: Compare the switches physically. Do they have the same number and arrangement of terminals and connectors? If they look identical, the chances of compatibility are very high.

If you can't definitively verify compatibility, it's safer to purchase a new ignition switch specifically for your 1983 F-150 to avoid potential problems. The cost difference is likely minimal compared to the potential hassle of a non-functioning ignition.