1973 FMX Vacuum Modulator questions

Cougar Community Classic Cougar Maintenance Restoration and Repair
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Does anyone have the Ford parts book that tells the original part number for the vacuum modulator? It’s on a 2V 351C with federal emissions.

1973 is the first year for the dual vacuum modulator. The “normal” port goes to manifold vacuum. The port on the transmission side of the diaphragm goes to EGR vacuum. When EGR vacuum hits, I would expect that to increase the transmission control pressure since the EGR vacuum would be working against the vacuum on the manifold side.

It’s a push-in mount, not a screw-in mount.

Is there a difference between the modulator used on a 4V vs. a 2V application? What about FMX vs. C4 or C6?

Is there any indication what color band should be on it?

Thank you in advance

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For the C-6 A/T ( from 7/17/72 is the push-in type D3TZ-7A377-A ):

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For the C-4 A/T the push-in style is TM-15 / D2AZ-7A733-A ):
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and for the C/M ( 1968/ FMX ) the vacuum modulator is p/n C1AZ-7A733-B:
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1 Like
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For 1973 applications, the service replacement part numbers are:

C4: not used in 71-73 Cougars, but the Mustang app is D3OZ-7A377-A

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FMX: D3AZ-7A377-A

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C6: D4AZ-7A377-B

Motorcraft Automatic Transmission Vacuum Modulator Valve TM-29 D4AZ-7A377-B | eBay

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Thank you all for your replies.

It can never be easy. All the D3AZ-A modulators I can find are screw-in rather than push in type. For the time being I’ll be using the D3AZ-C modulator. When I get back up to my car again, I’ll need to look for the transmission tag and see if that helps.

Thanks again.