Plant: (7th Digit 78-81, 11th digit 82-88)
M=Lansing, MI
P=Pontiac, MI
H=Flint, MI
R=Arlington, TX
G=Framingham, MA
D=Doraville, GA
2=St. Therese, Quebec, Canada

Location Code 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
St. Therese 2 x x x x x x
Doraville, GA D x x x x x x
Framingham, MA G x x x x x x
Flint, MI H x
Lansing, MI M x x x x x x x
Pontiac, MI P x x x x
Arlington, TX R x x x x x x x x x

'79, '83 and '84 Hurst Olds were built in Lansing, MI
The first sequential number of the first '83 and '84 H/O's are 317432 and 379463 following the plant digit.
85-87 442's were built in Pontiac, MI or Arlington, TX however I have yet to see an '85 442 built in Pontiac, MI.
1988 Cutlasses were produced alongside the Chevrolet Monte Carlo in Pontiac, MI until late January 1988.