261 engine colors Greg Hill has some interesting information on replacement 261 engines. There might have been a few differences in replacement engines: differences with respect to what features/parts they had/used: parts used in the year of manufacture of the replacement block vs parts used in the year of the recipient truck. These would be things like type of oil filter and type of water pump. It looks like GM might have put recipient-year parts on the engine (water pump and oil filter and ??).
