Unfortunately, lots of people voice opinions without knowledge or experience. The Poly engines and early Hemi's are very similar to our over designed LA and big block engines. Not really any weaknesses, other than stated above, lack of High Performance parts and being overshadowed by newer engines. They were never offered in an "A" body. I had one in a push button automatic 64 Dodge Polara and loved it. All Chrysler based engines were way ahead of the competition in design and durability.