I have determined (fingers crossed) at long last that my intermittant run problem stems from a faulty hall sender (impulse sensor). My '83 falls into that funky and short-lived period when several distributor components were used. It has the Bosch unit with the round plug at the end of 5" of pigtail.

I want to convert to the hall sender with the rectangular plug used on the '84 because the original round plug unit runs around $290.00 (AC/Delco E1944C), while I can get the '84 rectangular plug hall sender for about $110.00 (Volvo PN 1237031166).

Even though both of these run with the same ICU (1317295), a mechanic very convincingly told me today that if I splice on the rectangular plug and use the '84 sender, I will risk frying the ICU because the "resistance values" from one to the other will be different. I don't get it. Who's out to lunch on this one, me or him?