Ford modulator valves

[junkyardjeff]

It seems there are more then one for a certain trans,the C-4 I am having issues with has three possibilities.  Red band with two vacumn ports and yellow and green with one vacumn port so what could the differences be and how can they effect the trans.

[Crosley.In.AZ]

use the green stripe... most common unit i use.

dual port modulator was used with main manifold vacuum on one port.. ported vacuum source on the other modulator port to aid in trans down shift at lower speeds during emission circus in the early 70's

[junkyardjeff]

Its got the green strip modulator on it now,I was wondering if there was a better one to use with the vacumn issue I am having with the motor.