cjnsharpe124,
If you bought that part recently from SNG, then you haven't bought a genuine CBC6766. This is because CBC6766 has been unavailable from Jaguar for some time.
SNG Barratt sell 3 types of parts:
- Genuine Jaguar parts. You can buy these direct from Jaguar Classic Parts or via any Main Dealer. SNG Barratt effectively operate as a Dealer and have a Dealer code to be able to use the Jaguar Parts ordering system. If you're buying a genuine Jaguar part, it's often cheaper to buy online direct from Jaguar, or to try and negotiate a discount from your Main Dealer (I can often get 10%- 20% discount).
- The second type of parts they sell are "OEM" parts. Parts that they have sourced from a manufacturer who should be one of the original manufacturers of the part for Jaguar. These parts are designated in their catalogue with a # suffix. I believe that the part you bought from SNG was CBC6766#.
- The third type of parts that they sell are where they have sourced it from a new pattern parts supplier. They should be the same as the original part, but there is no guarantee. These parts are designated in their catalogue with a * suffix. On occasions, I have seen some quite good pattern parts, but I have also seen some dreadful ones. Personally, I would never fit any pattern parts unless I really couldn't get hold of a genuine part or a known OEM part.
So, CBC6766# SHOULD be a direct replacement for the original hub dust cap. But if your hubs are original and you don't have corrosion buildup in the inner flange, I would be minded to send the caps back to SNG and ask for replacements. And if the replacements don't fit, I would send them back and explain to SNG that they have a quality problem from their supplier.
I know it's only a rough photo but this non-attributed part that I found on ebay seems to have the correct dimension:
https://www.ebay.co.uk/itm/360945556528 ... R4aDx-GaZA
Good luck
Paul