the instructions should tell you which one to use....
which should be the heavier of the two
Small Block Chrysler - We provide one damper model that can
be used without a counterweight for internally balanced engines,
or use one of three supplied counterweights for other engines.
The 80012 and 90012 Dampers will fit the following applications:
a. All internally balanced 318 V8 standard and Magnum, all
internally balanced 273 and 340 engines w/forged cranks.
No counterweight is used with any of these applications.
b. 340 externally balanced 1972-73 engines w/cast crank.
Use supplied 91014 counterweight.
c. 360 externally balanced 1993-97 engines w/cast crank.
Use supplied 91013 counterweight. Will not work with '93-'97
5.9L Magnum engine.
d. 360 externally balanced 1971-92 engines w/cast crank.
Use supplied 91012 counterweight