The air cleaner change is usually mostly because the factory air cleaner mounted to the intake manifold suffers from bracket failure. Some may have done so for performance reasons. 1985 CA engines had a frame-mounted air cleaner. I installed one on my 1984 engine (see "No more whole lotta shaking ..." post).

Whatever redesign, you need to route the PCV blow-by gases to the inlet of the turbopump and need to manage the entrained oil drops. The 1985 CA design just ran it straight in, oil and all. Some people use an aftermarket oil catcher (ebay). I ran a tee off the PCV tube to the oil drainback tube in my 1984 engine, and similarly in my 1985 CA car since it now has an earlier engine. Note that 1985 CA engines don't have that drain tube nor was the boss for it machined in the upper oil pan.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans