[Mr70]

Whats the VIN# & Mileage.
The "SP" stumps me..Can you be sure of it's time period when applied?Meaning not put on in later 70's or 80's?
Could be a parking sticker for a specific lot someone worked at.Or a High School parking lot sticker.Just a guess,I'm not familiar with it.

I have seen a few of the GM Proving grounds Chevelles.To date I have 5 buildsheets stating this,and all are LS6's.
GM would pluk a few off different plant lines for quality control at that time and test them at the Warren Michigan,or Mesa AZ. facility.These were prrobably passed onto magazine editors to test for their issues as well.
Can you give color combo and more details on his Chevelle?
It may just be one of the LS6's tested in 1969 Motor Trend,HotRod,CarCraft Magazines,etc.