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According to the install manual in our own technical manual the hole should be 1-3/8” not 1-3/4”. (I am in the process of drilling mine right now) If the hole is 1-3/8” this is the grommet for it. MB# 113 997 00 81
Mike,interesting question. I guess the heater holes would be 35mm(1.377 inches) While the AC holes are spec'd at 1-3/8" (1.375").