I have the R4 in my 1984 & Sanden in my 1985. Both cool about the same, which is marginal on our >100 F days. I don't know why an R4 wouldn't work as well. Both have many mini-pistons w/ flapper valves. I think people ding the R4 more for durability, which is probably from poor lubrication. Read up on Hella's PAO 68 oil (Duracool or ebay), which stays in the compressor better. I suspect a parallel-flow condenser would help the most. You can tell how critical the condenser is if your temp switch becomes erratic (like mine) and doesn't run the electric fan when idling.

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