[Aurornis]

> My experience comes from driving and working on a 1988 GMC 6000 truck with an anemic 350 small block with a Muncie SM465 behind it. There was no catalytic converter,

Catalytic converters were required on most vehicles starting in 1975 in the US and the requirement was expanded to cover all vehicles in the early 80s.

Your truck was modified by someone.

[mulmen]

I don't think that's right. I believe this is the relevant EPA regulation: https://www.govinfo.gov/content/pkg/CFR-2004-title40-vol17/p.... This mentions emission limits but does not require a catalytic converter for medium duty (14,000lb-26,000lb GVWR) trucks like the GMC 6000.

[Aurornis]

> This mentions emission limits but does not require a catalytic converter

IIRC, technically if the vehicle meets emissions limits without a catalytic converter then it doesn't need one.

The emission limits are set such that a catalytic converter is required to meet them. They don't have to say "catalytic converter required" but the targets are chosen so that a catalytic converter can reasonably achieve them.

If the laws simply said "catalytic converter required" then manufacturers could put a tiny little square of catalyst in the exhaust and call it a day. Formula 1 isn't the only place where rules have to be written explicitly to avoid clever workarounds.

[mulmen]

> Catalytic converters were required

You claimed they were required by law, but they weren’t. Now you claim they had them anyway, but I can find no evidence of that either. Do you have some evidence that 1988 GMC 6000 trucks had a catalytic converter from the factory? I can find nothing online to support that claim.