I have never found any documentation on the engine colors, but, I also have a late 1929 (sold in August 29) Chrysler Model 70 I purchased in original condition in 1964 with 42,000 miles. The engine was black and the color under everything that was taken off the block was black. The head was silver. I have a copy of the delivery order for my car from Chrysler archives and it came out of the Jefferson Plant August 7, 1929. Not sure if two engine colors were used that year? Based on the August 1, 1929 Model 70 parts list there were 2 different part numbers for the blocks (before and after block number V-13858). There are also three different cylinder head part numbers listed (Silver dome, Red head, and no color designation).