I have a holley carb in my '68 Malibu.. The listing number on the choke air horn is "R84020 1590". I haven't been able to locate it on any reference sites. Any help would be greatly appreciated!

It's listed on Holley's web site.

Here is a good site for more information:

http://www.mortec.com/carbs.htm

I referenced the mor tec site, however, I was unable to find any 4020 listings. Plenty of 4010 & 4020 refs of course.

Thanks..

It is a 600cfm carb. Here is Holley's list book>>>>Holley List numbers (http://www.holley.com/data/TechService/Technical/Carb%20Numerical%20Listing.pdf)
Your is on page #21

Thanks Jim!