On point #1 above: From two reports that showed 1969 model year production, both had 2 RPO ZL1 listed. If I recall, one report was through September 1969, and then the second report showed all of 1969 including the extended 1969 model year. Both reports showed only 2 RPO ZL1. These documents were sourced from magazine articles and previously published lists and were not found in the GM Heritage Center with the other trove of ZL1 related documents.

On point #2 above: That is what the internal GM documents from GM Heritage Center seem to indicate.

However, I think the second point is likely stronger: the internal GM documents indicated that "12-9-68" was the first "parts availability" date for an RPO ZL1 engine available at St. Louis plant for installation into a production Corvette. From what I understand, GM did not leave rare engines sitting around to be installed sometime well into the future, thus these documents seem to indicate the first RPO ZL1 was built on or slightly after 12/9/1968 given documentation shows that the Daytona Yellow ZL1 was definitely a RPO ZL1 and it was built in September 1969.

An additional important discovery in internal GM documents found at GM Heritage Center was that the type L88-engines were actually built with closed-chamber, despite the original CEC engineering plan for them to be open chamber (which was what appeared in various magazines in period). However, a "Stop Order" was placed on the open-chamber L88/ZL1 engine due to problems with the aluminum cylinder heads, which extended the closed-chamber models (including IT L88) for the 1969 model year way beyond the original engineering timeline. I don't have the data in front of me, but I believe this stop order was lifted sometime in the March 1969 timeframe, likely coinciding with the Camaro ZL1 engines released for "production" COPO 9050 Camaros starting with chassis #3. The first two "red hot" COPO Camaro ZL1s were requested by Pete Estes to ship out by December 31, 1968, for homologation/racing purposes and were not "customer" cars. As this was a production engine reliability issue for the ZL1, the lifting an engine stop order would probably have applied to Corvettes and Camaros at roughly the same time.

Additionally, the “427 CUBIC INCHES ZL1” console trim plate/badge (part number 3958746) was also marked on GM internal document Notice of Production Change C69-39 with the handwritten "12-9-68" date.

----Much interesting stuff! My 69 L88 that I bought with less than 3,000 miles from the original owner absolutely had open chamber heads. I haven't owned the car for many, many years but can't forget that as I removed the heads myself! One thing I can't remember was weather the production date was April or May of 69. I have multiple pics of that Monaco Orange convert, but did not retain any of the paperwork when I sold it to a Wisconsin collector in 1974-5.....Bill S

Im not a Corvette guy.
Believe this is a Prototype but I dont know if its a ZL1.
Sitting next to the Z/427 Camaro.
Someone posted these Pictures here on Yenko.net some years ago.

What's the deal with the windshield shape on that Corvette?

Looks to be a 70-72 nose, and odd treatment on the windshield. I don’t believe it’s the same car?

That C3 was a version done by Bill Mitchell. The windshield and mirror's are a giveaway. I'll search for some pictures I have, it's called the Aero Coupe.

Here's the Aero Coupe designed by Bill Mitchell. It was at Road America in Corvette Corral many times in the 70's. I believe it carried a ZL1 motor. I helped them unload it from the GM trailer one year, probably 1977 or 1978. I had my customized 1969 Corvette in the Corral and the driver liked it and asked me to guide him out of the trailer.

----Tim,,, One of my favorite Bill Mitchell concept Corvettes. I believe Ralph Eckler made a mold of that rear spoiler. Love the sidepipe covers!.....Bill S

Bill, what happened to that car? It sure was beautiful with lots of unique features.