I bought this for my previous Alfetta and it bolted directly to the
2 piece cast iron headers that were on the car when I bought it.
I was not aware that there was a USA version of this 2 opening downpipe.
The only other downpipe I've seen on Alfettas is the single lower pipe for the lousy 4 into 1 cast iron header.
Maybe ring up Centerline and ask them.
Here's a chart of the ANSA offering from back in the day.
It looks he same to me based on this ad.
I hope it helps!