Did I stump the experts? I thought it may have been the accessory's like the fuel pump with a double spring on the earlier cars or the AC compressor. I do not know of any internal engine differences.
I just now saw this thread. The written word can be taken different ways, some phrase 's ARE innocent but come across demanding or insulting so as to solicite a response. Others are not so innocent and are demanding or insulting so as to solicit a response.
Since I know you as I do I am certain it was meant in a friendly teasing way. More polite way and one that would not be mis interpreted would be to ask the question again in order to bump the thread
. I for one do not respond to threads that appear insulting so as to solicite a response. Just my opinion. FYI I am not sure in this case but suspect it may have something to do with the change out of valve covers at the engine plant on a Shelby unit since the engine was painted with sheet metal covers and then changed out.