Researching the L74 for another thread (https://classicoldsmobile.com/forums...very-rare.html) uncovered something startling.
I knew that some RPO codes meant different things for different years. But I've discovered that there is at least one code that means different things *within* a year, yes, at the same time:
In 1967, L74 is an engine code for both the 330 and the 425. So it ends up being "model specific" in 1967!
As if things weren't difficult enough.

(BlueVista will be glad to know his "confusion" was well founded!)

 

This really has nothing to do with engines, but in 1992 I ordered a new Bravada for the wife. She wanted it in white w/grey cloth interior. About 5 weeks into the order, we stop in to ask the salesman how things were. He's explaining to me that when he put the color ext. color code in, I think it was "D", which was white for olds at the time, EXCEPT that "D" was the code for black ONLY for the Bravada. Now, I'm trying to explain to the wife, and she asks me,"I'm going to have a black and white truck?" Needless to say, they knocked a BIG chunk off of that trucks price.

 

You got it.

 

That might be unusual when it comes to engine codes, but it's not so unusual for other RPOs. M40, C60, and F41 meant TH400, A/C, and HD suspension no matter what model they were on. But the individual components varied depending on the model. So maybe in 1967 "L74" meant "performance engine", but for one model it was a performance version of the 330 and for the other a performance version of the 425. Using the same logic, they could've lumped the W30, W31, W33, and W34 all under the same RPO, since they were all for different models.

 

Sure, but the point is that they *didn't* lump them together. And they rarely did such a thing.
Thus it wasn't *logical* that they did it at all then!