The table at the end was poorly constructed. It says 3-hole, which is also my recollection.
1967-'76 Camaro, Firebird
1970-'76 Monte Carlo/Malibu
1964-'76 Chevelle
1977-'79 12.7:1 quick-ratio gearbox
Line Thread Size: 11/16 x 18 and 5/8 x 18
Number of Mounting Holes: 3, (missing leg H-pattern)
Input Shaft Diameter: ¾-inch
Output Shaft Diameter: 1 ¼-inch
Number of Turns Lock to Lock: 2 ½- 3