S code Mustangs are not particularly rare; there is an S-Code registry on the net w/ substantial membership & car examples. I wish people would quit referring to the '69 S-code as a GT engine. Ford quit using the GT description for the S-Code after '68 and in fact lowered the HP rating of the 390 4V Mustang engine for 1969 while using the same code. You got the exact same 390 in an LTD or Country Squire for 1969.