* Specific engine code: The exact engine code (cast into the block) matters. While both are 350s, there were variations in things like valve size, combustion chamber design, and bolt patterns (though less likely between consecutive years). Ideally, you'd want to match the engine codes for the best fit.
* Minor variations: While usually interchangeable, there *could* be very minor differences in things like intake manifold bolt patterns or accessory bracket locations. These are usually not show-stoppers but might require slight modification or the use of different gaskets.
* Condition: The condition of the heads is paramount regardless of the year. Cracked heads, warped surfaces, or damaged valve guides will cause problems regardless of the engine they're installed on.
In short: It's *highly probable* they'll work, but comparing the engine codes (e.g., a L03, L69, etc.) from both engines is crucial for absolute certainty. If the codes differ significantly, consult a parts catalog or an engine rebuilding resource to confirm compatibility.
