Why is there a chevy dizzy in my 360?

Sorry, so what you're saying is the round piece with the rubber o ring that seals the unit to the block is mopar specific?

I can't see well enough in your photos. NORMALLY the "part that fits the block" "IS" the entire distributor housing, like so:



If that is "the case" pun intended, then the label must be incorrect.

However if it's a separate piece down near the block, then someone MUST have taken that Holden distributor and machined the case and shaft, as well as machined a mount bushing.

Years ago, when I adapted the 'Vette distributor, I took a junk Mopar case like in the photo, sawed the bottom off, and machined a hole in the middle to fit the Chev distributor mount flange. Then we cut off the Chev distributor case, shorted and tanged the shaft end to fit Mopar

If this has been done, you should be able to see it easily.

If not, it simply has the incorrect part no. on the label.......