I have no idea if the 126 and 123 pods use the same internal parts. I believe that all the pods on my 84 SD use the same diaphragms. It would be easy for me to believe that nothing changed except the inlets and outlets locations from the pods on your car and mine.
I'd suggest that if you find one common to both car you can believe that those diaphragms sold by the guys in Oak Ridge will fit your car. Giving them a call might be the easy way out.
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