I have found that there is are two different 2.0 plenums. One has a 13mm and 6mm (?) port and the other a 13mm 10 mm ports.
I think the split is probably 73-74 and 75-76. But not sure which plenum fits which years.
Full Version: 2.0L Plenum vacuum port sizes and fitment ?
The two big ones are the 73.
think I posted about this a while ago somewhere with pictures comparing the two.
There are other differences as well, most noticeable is the width of the throttle cable support.
These changes coincide with changes to the throttle body, airbox, and oil tower vent that occurred for the 75my mainly around the crank case venting/elimination of the PCV.
But as stated, the one with the 2 large ports and also the narrow throttle cable support is the earlier version. The later (75+) configuration does not use the rubber stacked vacuum elbow, instead it connects the smaller vacuum line from the decel valve directly to the plenum.
I have found that there is are two different 2.0 plenums. One has a 13mm and 6mm (?) port and the other a 13mm 10 mm ports.
I think the split is probably 73-74 and 75-76. But not sure which plenum fits which years.
There are other differences as well, most noticeable is the width of the throttle cable support.
These changes coincide with changes to the throttle body, airbox, and oil tower vent that occurred for the 75my mainly around the crank case venting/elimination of the PCV.
But as stated, the one with the 2 large ports and also the narrow throttle cable support is the earlier version. The later (75+) configuration does not use the rubber stacked vacuum elbow, instead it connects the smaller vacuum line from the decel valve directly to the plenum.
QUOTE(bdstone914 @ May 18 2022, 07:55 AM) 
I have found that there is are two different 2.0 plenums. One has a 13mm and 6mm (?) port and the other a 13mm 10 mm ports.
I think the split is probably 73-74 and 75-76. But not sure which plenum fits which years.
QUOTE(emerygt350 @ May 18 2022, 09:37 AM)
The two big ones are the 73 (& 74).
Correct. Use of a stacked elbow for correct vac. lines is necessary. The 75 (76) plenum used the smaller ports & did away with that elbow.
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