For a ‘70 Cutlass Supreme with an original open differential (12 bolt cover/10 bolt ring), which company carries a good aftermarket cover? I started looking at Summit but when I narrow down to make/model it only shows me 10 bolt covers. OPGI was a bit pricey but if that’s the correct ones I’ll go for it. Any thoughts?

 

The only one for the O-Type may be the W-27 cover from one of the resto houses.

I did a quick search and The Parts Place had the lowest price I found:
https://www.ebay.com/itm/1964-72-Old...sAAOSw6eZah0e~

 

^^^This. No one reproduces the stamped steel cover. There isn't the demand for it.

 

Thank you!

 

Some covers aren't a good idea. The factory has the oil slinging around and coming back up and splashing on the ring and pinion but some of the fancy aluminum replacements don't do that. This goes especially for big pickup trucks. The Olds W27 cover is probably better engineered than that but I don't know what it looks like inside. I think it was Gale banks did a video on it.

 

I think LPW still sells a 12 bolt olds girdle aluminum cover.

301-12O
311-12O