I mentioned in the Mac-Ink t-shirt post that my old t-shirt was getting long in the tooth. Then I realized that ~I~ was getting long in the tooth as well. With another birthday coming up, I realized that the number of birthdays I have left are becoming less and less. I used to not care about birthdays, but I'm now getting to where I certainly would welcome making it to the next one. 
With that, I decided that while I don't know everything I need to know about G-bodies, I've got a pretty good handle on working my way around one. So rather than die with all this junk in my head, I may can pass along some of the crap that's taking up storage space.
So, I decided I'll try my hand at a PLOG. "Parts Blog" kind of thing. I don't know where this will end up, but hopefully, it can enlighten and educate. I'm the first to admit, I'm not an expert. I grew up in a GM family, but I was never a GM employee myself. But I've spent so much time at the GM dealerships at the parts counters and listened to all my dad's stories about the inner workings of Chevrolet and Corvette, I've learned a few things over the years. "I'm not a GM parts jockey, but I play one on TV."
Obviously, if any of this needs correction, pipe up. We're all here to learn.
First up: Super Stock wheels with snap on center caps.
I've seen ads everywhere for these. But the reproductions are out there as well, so be careful. They're all expensive nowadays. An interesting point about the ads seemingly many love to use the casting number molded on the inside of the cap as the part number. Likely because they don't have the parts box, or saw it other places while trying to figure out what catalog number to use. While technically 416393 is a part number, it's an engineering number not the catalog number. (Some are the same, but many aren't). Many ads use #416393 because a lot of the time, they don't have the box. But this can be misleading.
Engineering part numbers were assigned for every single part that makes up your G-body. But as you know, some parts you get from GM come as an assembly, made up of several parts. Thus, it doesn't make sense to use the engineering part number for the catalog part number. This is why you see one number "cast" into a part, but then the catalog number is completely different.
In case anyone is looking for them by GM part number, aka catalog number, it's technically 552293 for the cap assembly. They use that number to look up parts in the GM service and parts operations system, or GMSPO.
Snap on with Olds Rocket emblem in the center. Engineering number is really the original part number of the chrome cap piece of the puzzle, which may or may not end up as a catalog number depending on the assembly. Since the cap includes retainer (catalog/engineering part number 416394) and the center stick-on emblem (catalog part number 554457). Note the very early caps came as the cap and retainer, but the decal was separate and needed to be stuck on the cap. Later, the cap came in the box with the decal already on it. GM always tweaked the parts operations so in different years, they did different things.
Used on all Super Stock wheels made for snap on caps with a couple exceptions. And those are the huge "Starfish" caps on Delta, which covered the lug nuts too, and for the 85-87 442. The 442 they come under a different catalog number, GM p/n 22528777, but use the same casting (engineering) number of 416493. Only difference is the center rocket decal was replaced with a black/gold "442" decal on the 442s. See below.
As far as repros, ALWAYS ask to see the back of the cap to determine if it's a genuine GM part. If they refuse, then you probably shouldn't buy it. Unless you don't mind repros. The aftermarket ones do not have the casting numbers/marks that you see in the genuine caps. Plus, from what I've seen, the repros have 5 circle marks inside where the genuine caps have 3 prominently raised circle nubs, and usually bigger screw heads on the retainer. Example below.
With that, I decided that while I don't know everything I need to know about G-bodies, I've got a pretty good handle on working my way around one. So rather than die with all this junk in my head, I may can pass along some of the crap that's taking up storage space.
So, I decided I'll try my hand at a PLOG. "Parts Blog" kind of thing. I don't know where this will end up, but hopefully, it can enlighten and educate. I'm the first to admit, I'm not an expert. I grew up in a GM family, but I was never a GM employee myself. But I've spent so much time at the GM dealerships at the parts counters and listened to all my dad's stories about the inner workings of Chevrolet and Corvette, I've learned a few things over the years. "I'm not a GM parts jockey, but I play one on TV."
Obviously, if any of this needs correction, pipe up. We're all here to learn.
First up: Super Stock wheels with snap on center caps.
I've seen ads everywhere for these. But the reproductions are out there as well, so be careful. They're all expensive nowadays. An interesting point about the ads seemingly many love to use the casting number molded on the inside of the cap as the part number. Likely because they don't have the parts box, or saw it other places while trying to figure out what catalog number to use. While technically 416393 is a part number, it's an engineering number not the catalog number. (Some are the same, but many aren't). Many ads use #416393 because a lot of the time, they don't have the box. But this can be misleading.
Engineering part numbers were assigned for every single part that makes up your G-body. But as you know, some parts you get from GM come as an assembly, made up of several parts. Thus, it doesn't make sense to use the engineering part number for the catalog part number. This is why you see one number "cast" into a part, but then the catalog number is completely different.
In case anyone is looking for them by GM part number, aka catalog number, it's technically 552293 for the cap assembly. They use that number to look up parts in the GM service and parts operations system, or GMSPO.
Snap on with Olds Rocket emblem in the center. Engineering number is really the original part number of the chrome cap piece of the puzzle, which may or may not end up as a catalog number depending on the assembly. Since the cap includes retainer (catalog/engineering part number 416394) and the center stick-on emblem (catalog part number 554457). Note the very early caps came as the cap and retainer, but the decal was separate and needed to be stuck on the cap. Later, the cap came in the box with the decal already on it. GM always tweaked the parts operations so in different years, they did different things.
Used on all Super Stock wheels made for snap on caps with a couple exceptions. And those are the huge "Starfish" caps on Delta, which covered the lug nuts too, and for the 85-87 442. The 442 they come under a different catalog number, GM p/n 22528777, but use the same casting (engineering) number of 416493. Only difference is the center rocket decal was replaced with a black/gold "442" decal on the 442s. See below.
As far as repros, ALWAYS ask to see the back of the cap to determine if it's a genuine GM part. If they refuse, then you probably shouldn't buy it. Unless you don't mind repros. The aftermarket ones do not have the casting numbers/marks that you see in the genuine caps. Plus, from what I've seen, the repros have 5 circle marks inside where the genuine caps have 3 prominently raised circle nubs, and usually bigger screw heads on the retainer. Example below.
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