In the Yo, ken dept, its not a cleveland. Ken " Ive neverseen or heard of a 351 windsor in a 71 mustang. ' a rare mustang" What the CHEVY ? icant believe yu didnt do your homework before publishing that answer it makes it sound like you dont know what your talking about. Heres the skinny in 1971 ford offered both the Cleveland & the windsor, guess what they were both H codes 5 # in the vin soo you had to physically look @ the engine to see what you had both H codes engines were 2v & thats not 2 valve either. the cleveland in stock form would run circles around the windsor which was basically a truck engine, I also have 2 1971 mustangs mach-1's one has an H code cleveland the other an H code 351 windsor one is not more rare than the other. you look in the jerry heasley books or do a general search on the web either way you missed it big time on this ????