in the 550 market and have been trying to learn as much as possible about these cars. i came across the sheehan article on the 550/456 cars and it mentions the problems of the early cars having excessive oil pressures and the simple spacer fix. what exactly is done to correct this problem? and what sort of pressures were being seen before and after the fix? if you had two early cars, one fixed and the other not, would you be able to tell by the oil pressure guages assuming both cars were warmed up etc in a side by side comparison? thx.