Prepare and roll out pastry.
Line a 9-inch pie plate.
Trim pastry to 1/2 inch beyond edge.
Flute edge; prick pastry.
Bake in a 450° oven for 10 to 12 minutes.
Separate egg yolks from whites; set whites aside for meringue.
For filling, in saucepan beat egg yolks slightly; add sour cream and vanilla pudding mix, stirring to mix well.
Stir in milk and thawed lemonade concentrate.
Cook and stir till thickened and bubbly.
Pour hot lemonade mixture into baked pastry shell.
Make Meringue for Pie using the 3 reserved egg whites.
Spread meringue over hot filling; seal to edge.
Bake in 350° oven for 12 to 15 minutes.
Cover; chill to store.