Firebird fan chart per '73 service parts index

9794230 4 blade, 17 5/8" diam
6 cyl not AC or HD

9788982 7 blade, 18" diam
6 cyl AC or HD

9796372 7 blade, 19 1/2" diam, 2 1/4" pitch
'67-'68 V8 w/ AC
'69 V8 w/ AC (thermo control)

9798940 4 blade, 19" diam, 2 5/16" pitch
V8 exc. AC, A.I.R. or HD
'67 326 w/ A.I.R. except AC
'67-'68 400 Ram Air
'68 V8 w/ auto trans and 2bbl except AC
'68 V8 2bbl HD or AT except AC
'69 V8 exc. AC or HD

9777012 7 blade, 19.5" diam, 1 7/8" pitch
'67 400 exc. AC or Ram Air
'67 V8 (thermo control)
'68 V8 except AC

9779005 5 blade, 19" diam, 2 1/4" pitch
'67 V8 HD exc. AC

480033 5 blade, 19" diam, 2 5/16" pitch
'68-'69 V8 400 4bbl exc. AC, HD, or Ram Air

9796135 7 blade, 19 1/2" diam, 2 1/2" pitch (flex)
'69 V8 HD

Kurt, I have one of the 9794230 if you can find a 9798940 to measure.