1999 Ford Contour no 1, 2 d, od, or reverse

Driving down road at 40 mph heard a clunk, thought I drove over something. Approx 150 yds more another clunk now I don't have 1, 2, d, od or reverse. Discovered that my servo cover is rusted out. Is it my whole tranny or an easy fix. Fluid looks good no metal shards and cv shafts are good?