Could a 67 Camaro built late November with a 4P on the cowl tag possibly be a Z28? I heard some of the early 67s used this designation.

Nope, first Z28's did use the 4P but they were built the last week of December 1966. there was one prototype built before that, but beleive it was a late September, or early October car. That car was used to demonstrate the 302 to GM brass and shown to some car magazines.

Is this that car? http://www.1967z28.com/articles/mtfeb67.html

Yep, 67 people refer to it by the license plate number LM-640.

does anybody know how many z 28 cars were built the last week of dec 66
with the 4p code just wondering ?

I really don't think anyone knows this one. I have tried to find the same answer. Back in 1999 I was investigating a Januanry built 67 RS that had the 4P code but no SS emblems, only RS. 4 speed, 3:73 posi rear, power disc brakes, traction bar, and factory tach. Had a 69 model 390 horse 427 in it. Turned out to be a 275 horse 327 car, but had me going for a few days.

Does anyone know the earliest known date for the 4L code?

Lynn