Yes, my inital reaction as well.  It seems the numbering on 553's don't last  

Grizzly (Aussie Mainline)

waz, no problem, i was just deciphering the numbers, regards bill

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

sorry Bill, I think it's a 553 as it has the rear throttle linkage mounts one shortened to fit later dizzy. (hard to find one than hasn't) 573 had a vacuume port on the rear for the vacuume advance. 

Grizzly (Aussie Mainline)

Edelbrock 573

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

What is this intake Ebay #310314564876?

56 VIC  Gene Stoehr Sr.