From the Pulley Spreadsheet in the Library Section, two (2) water pump pulleys were used for 1969 Cobra Jet cars with smog & no AC. The distinguishing factor between the two pulleys in the spreadsheet is the car's rear-end axle ratio.
The Mustang 428 CJ Registry Website lists the same two water pump pulleys, but their distinguishing factor between the two pulleys is the car's build date.
Which is the correct distinguishing factor?
I'll be using one of these in my March 17, 1969 built Q-Code Convertible, which has smog and power steering, no a/c, 3.5:1 axle ratio.
Thanks in advance.