Anyone see these rotors before ?

[76dart/6]

Hey what's up FABO !
Changed my rotors because i had a strange wobble I was tracking down ,the process was straight forward but there was 4 holes in the hubs . I haven't seen this before .I'm no mechanic just keep my cars up to snuff myself but idk if these holes in the hub are the norm? . The replacements did not have these holes. Pic is attached .
Car is 1976 dodge dart with a slant 6 all stock minus the qa1 UCAs.

 

[Demonracer]

They were just cast at a different foundry would be my guess. Besides, it saves weight on the front end. LOL

 

[76dart/6]

They were just cast at a different foundry would be my guess. Besides, it saves weight on the front end. LOL

Ok.thanks for your response
. As long as it wasn't some tweaky stuff the previous owner did haha

 

[Demonracer]

No, I've seen those type rotors before but I never questioned why the holes were there.

 

[Dana67Dart]

Might be for balance, rather than adding weight. We have all see huge weights put on drums

 

[RustyRatRod]

Those are balance holes is all. It was heavy on that side and had to be lightened up. Perfectly normal. Some have the holes and some don't.

 

[76dart/6]

Thanks for everyone's input.

 

[66fs]

Those are balance holes is all. It was heavy on that side and had to be lightened up. Perfectly normal. Some have the holes and some don't.

Usually seen on OEM rotors only.