Matt, you're remembering it wrong...here's a table breaking them down by year. A '74 may have a 3.36, but it would be an R180.
Standard Rear End's as Delivered From The Factory 1969-1989 :
240Z 70-73 MT (3.364) (R180)
240Z 70-73 MT 5spd. (3.900) (R180) - non US
240Z 71-73 Auto (3.545) (R180)
260Z 74 MT (3.364) (R180)
260Z 74 Auto (3.545) (R180)
280Z 75-76 (3.545) (R200)
280Z 77-78 MT (3.545) (R200)
280Z 77-78 Auto (3.545) (R180)
280ZX 79 MT,4 Spd,2 Seater (3.364) (R180)
280ZX 79 MT,5 Spd,2 Seater (3.364) (R180)
280ZX 79 All With Automatic(3.545) (R180)
280ZX 79 MT,4 Spd,4 Seater (3.364) (R200)
280ZX 79 MT,5 Spd,4 Seater (3.7) (R200)
280ZX-GL 79 (3.7) (R200)
280ZX 80 MT,2 Seater (3.545) (R180)
280ZX 80 Automatic 2/4Seat (3.545) (R180)
280ZX 80 MT,4 Seater (3.9) (R200)
280ZX-GL 80 (3.9) (R200)
280ZX 81-83 Automatic all (3.545) (R180)
280ZX 81-83 Turbo - all (3.545) (R200)
280ZX 81-83 MT (3.9) (R200)