the real issue with putting a 3.6l in a more narrow 66 is the exhaust
I struggled with it in my wider 1972. I would be concerned its even possible on a early A-body.
The center exhaust ports dump exactly in the narrowest part of the chassis. The Inner fender blocks it on the right.
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The steering coupler is even closer on the Left. Forget about power steering unless its a rack & pinion.
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