Jim! I totally agree with you. But after hours of searching and thinking, the only thing I can come up with is that they used power tools.
They hanged the complete system and then started to tighten the bolts from the back and moved forward. Before that they mounted the rear rubber bracket and the rear steel bracket above the rear end.
The notch needed to be so much open to accomondate a power tool to bolt the resonator to the rubber bracket.
That is the only thing I can come up with.
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