Product review (4 stars): Be sure to view the video!
We have a Whirlpool WDT780SAEM1. The box arrived without instructions and partially opened (indicating that it was a return). So H/T to K2D2, who pointed out the YouTube video that provides precise directions (search "W10712394 V-rail"). Using the video, the fit was perfect, and took less than 20 minutes to complete.