well with hardforums being down we need somewhere else to show off out work. j/k well here you go...
Correction if you are looking for it by car.
http://www.heatercore4u.com/2-199.htm
I think it's this one and the cars they have it listed for are.
Caprice / Impala
1971-76 all
1977-1990 w/o air
or
http://www.heatercore4u.com/2-202.htm
Caprice Impala
W/O A/C 1970-69
or
http://www.heatercore4u.com/2-302.htm
W A/C 1990-77