Swapped out my low beam T3s for Sylvania halogens tonight on my '72 Supreme, and I noticed that the prongs on the Sylvanias have little "nubs" that stick out, so the plug won't slide all the way down to the base of the prongs...they stop maybe 1/2 way. The plugs are nice and tight and my headlights work, so do I need to worry? You can see them in this pic...

 

No need to worry. Push the connector until it bottoms out on the stops.

 

Yeah, the purpose for the stops is to prevent pushing the connector on too far.