5. The length of the advance slot in the points-cam assembly varies by application. Both of these examples were removed from original Pontiac distributors. When compared to the unit at left, it’s quite easy to see just how much longer the slot is on the unit at right. The cam assemblies are also generally stamped with a partial part number. If you have more than one points-cam assembly available, it’s generally best to select the unit with the shortest advance slot for best results.