L31 RPO Code???

so, im decoding my RPO codes, and so far all is well...except when i got to the engine code which is "L31." this is what it says:

L31 : 409 CID V8 400HP (SPECIAL HIGH PERFORMANCE-SOLID LIFTER CAM)

i thought that it had a Vortec 350? can anyone clear this up for me please, thanks!

ZOOM, ZOOM, ZOOM!!

Police edition or anything? Sounds super cool if you got an upgrade you didn't know about.

I don't have any idea about the code, but keep updating as you find out.

post a pic of your engine and engine id (on the left if your faceing the engine big white sticker, next to the fan guard)