PK is usually Plymouth Police
Was this car ordered PL then later fitted with police equipment?
I see the police package code (third row from top).
"A38" car, or "police package" equipped almost any second-digit (price class) VIN car, including "K"'s, plus some "F" codes, with heavy-duty brakes, heavy-duty high-amp battery with heat shield, bigger capacity radiator, 140 mph speedometer, etc.
i dunno if fleets could get a "K" equally equipped to a L,M,P,/A38 rig ... i am sure they could get pretty close though. as long as they (fleets) got the hot mills, big brakes, body reinforcements they'd be happy i think.
in the end, I suspect "L" price-class cars, essentially tricked out like a "K", was cheaper maybe?
Also, they ("fleets") frequently bought "M" and "P" models, then slapped "A38" police content on them, for detectives, chiefs, and other departmental brass. cop cars capability with creature comforts as a perk for the muckety-mucks' take-home/assigned rigs.