Besides Earnhardt and Rudd, and now Earnhardt Jr and Busch, how many times have two drivers traded places?

I seem to remember something along these lines, but never with as big a name driver as your two examples. I think Gani did it within his team with Jimmy Spencer and Casey Mears one year, but that was due to owner's points with the car numbers, to ensure Mears got seat time. And I think something similar happened with the Wood Brothers, either when they had Michael Waltrip, or Kenny Schrader, but Jayski would be the best source on this.