Two, and an El Camino. Have had a few other 1964-72 GM A-Body cars though.
1969 SS 396 L78/M21 (The one that got away)
1972 (my current car) LS5/M21
1972 Monte Carlo (current)
1968 Tempest (briefly drove this car in high school) 350 2bbl/ST300
1971 El Camino SS (bought as a project, sold to pay for college before I ever did anything to it)
My father has had a ton of them over the years...
1964 SS 2dr hardtop 220HP 283/M20
1965 300 2dr 283/3spd
1966 SS 396 360HP/M21
1967 2dr hardtop 327/PG
1967 El Camino L79/M21
1968 SS 396 L34/TH400
1969 SS 396 L34/M20
1969 Malibu 2dr hardtop 300 HP 350/M20
1970 Malibu 2dr hardtop 350 2bbl/TH350
1970 SS 396 L34/M21
1970 SS 396 L78/M21
1970 SS 454 LS6/M22
1971 SS 454 clone 454/TH400
1972 SS 454 LS5/TH400 (bought new)
1972 SS 454 clone (the green bean) 454/TH400