This spacer must be used when replacing an original balancer that is 3-3/8" long which were typically found on '79 and earlier 351W engines.
Harmonic Balancer Technical Notes (PDF)
This engine family used 1 of 5 common length balancers, use the following information to determine your application needed. They are made to early style length of 3" to allow their use in tight applications, but adding on with a spacer for pulleys listed below, you can fit almost any car and pulley combo. These spacers are unique and can only be used with the new balancers shown here. Pulley spacers listed are a 4 bolt design, but can be redrilled for the 3 bolt arrangement.
- 3" long - no pulley spacer required, white spacer adaptor ring can be removed from balancer
- 3-3/16" long - limited applications, use 91015366 (#81006) spacer and machine .090" off of 3 surfaces
- 3-3/8" long - use 91015366 (#81006) spacer
- 3-7/8" long - use 91015368 (#81008) spacer
- 4" long - use 91015367 (#81007) spacer
Typically found on '79 and earlier 351W engines with 3-3/8" long balancer.