[Terry M. Hunt]

On a 65 full size Pontiac was the 421 HO with Tripower the only engine that used 3 individual air cleaners like those on a GTO? The rest of the 421 engine options used the large painted air cleaner with 3 holes in the base?

[Stuart]

That's correct. You can see how the different engine options looked in the factory brochure, the engine configurations are shown on the page near the end: https://oldcarbrochures.org/United%2...rwe/index.html