Transmission Vacuum Modulator

[JohnJohn]

Guys,
My trans is shifting a bit off in traffic. It will pop into second quickly then is not down shifting when it should at slow speeds.
I want to replace the Transmission Vacuum Modulator to see if it fixes my problem.
I bought one yesterday but when I went to install it I noticed the one I have in my C4 is a screw in vacuum modulator and the one I bought is a push in.

Anyone know if I have a Bronco C4 or what year uses a screw in vs. push in?

 

[JohnJohn]

Google helped me.

Screw in - NAPA ATP 13671 C4 C6 Transmission vacuum modulator 1964-72

It looks like I may have a 64-72 C4.

NAPA sells a White, Gree, Red and Black modulator. I ordered the white and green ones. Guess I will try them out to see what color works best with my 33" tires and EFI mods.