speedmaster stuff pulled from Summit racing shelves
A lot of the designs in the speed parts industry just plain aren't possible to protect with a patent. And a lot of well-established speed parts have some level of copying - for example, Aeromotive was started by people who had left Essex Industries, and a lot of their pumps and regulators look a lot like Essex designs. Or Cragar S/S wheels - they were a way to make a cheaper copy of the Torque-Thrust by bonding a steel rim to an aluminum center instead of an all-alloy design. A lot of times if you tried to sue another company for copying a part, they could reply "Yes we did, neener neener neener!" and the judge would still toss the lawsuit out of court. Sorry, but that's just how the system is.
But trademarks are a much clearer line. Trademarks say that you built the part and it's you who stands behind it. This is especially important when knowing the dimensions of a part doesn't tell you what tolerances to hold it to, what can go wrong making it, or how to support it once it's in the market. It's easy to prove a trademark violation in court. There's no weaseling out of it if you clearly have somebody else's logo on the part. As such, Speedmaster should have known to treat any part that has someone else's trademark as radioactive, whether they have a hidden subsidiary selling counterfeit parts or had a supplier botch things.