Brake pad dampers are required to reduce squealing of the brakes by properly positioning the brake pad in the caliper.
There's a variety of dampers, and this table may help identifying which is which.:
| Type Year | used for | part (20)(31) | size | part (21)(32) | size |
| 77 - 82 | front caliper 928.351.425/426.00 | n/a | n/a | ||
| front caliper 928.351.425/426.01 | n/a | n/a | |||
| rear caliper 928.352.425/426.00 | n/a | n/a | |||
| 81 - 85 | front caliper 928.351.427/428.00 | n/a | n/a | ||
| front caliper 928.351.427/428.01 | n/a | n/a | |||
| rear caliper 928.352.425/426.01 | n/a | n/a | |||
| 86 | front caliper 928.351.427/428.00 | n/a | n/a | ||
| front caliper 928.351.427/428.01 | n/a | n/a | |||
| front caliper 928.351.421/422.00 | 928.351.096.18 | 42mm | 928.351.096.19 | 36mm | |
| rear caliper 928.352.425/426.01 | n/a | n/a | |||
| rear caliper 928.352.421/422.00 | 996.352.086.00 | 30mm | 996.352.096.01 | 28mm | |
| 87 - 91 | front caliper 928.351.421/422.00 | 928.351.096.18 | 42mm | 928.351.096.19 | 36mm |
| front caliper 928.351.421/422.01 | 928.351.096.17 | 44mm | 928.351.096.19 | 36mm | |
| front caliper 928.351.421/422.02 | 965.351.096.00 | 44mm | 964.351.096.01 | 36mm | |
| rear caliper 928.352.421/422.00 | 996.352.086.00 | 30mm | 996.352.096.01 | 28mm | |
| rear caliper 928.352.421/422.01 | 996.352.086.00 | 30mm | 996.352.096.01 | 28mm | |
| 92 - 95 | front caliper 928.351.423/424.03 | 965.351.096.00 | 44mm | 964.351.096.01 | 36mm |
| rear caliper 928.352.421/422.03 | 964.352.096.00 | 30mm | 964.352.096.01 | 28mm |
ps: I'm not 100% sure how accurate this really is. Any updates appreciated!