As im currently stock pileing engines & parts,What are the external differences between years of engine & whats the most desirable cores to start with. 2 of the engines we have,have raised ridges around the spark plugs,2 are not raised and 1 has an auto trans flex plate attached. Interesting question as when looking for seal kits the question always asks "what year is your engine" Duh I have no clue it was in a pile out back.
Dan