AFAIK...all of the plastic type replacement bushings will either require...or benefit greatly from.... a custom fit ( turning to a specific ID and OD ).
The problem is that you can measure and fit the ID of the bushing to the male portion of the A-arm... but once you install the A-arm, the outer "hold-down" part clamps on the OD of the bushing and distorts the precious fit you *thought* you had for the ID. Best to test fit and true the ID on the A-arm while somehow mimic-ing the clamping action of the outer, hold-down piece.
- Wil