The Lockheed XFV-1, the Douglas A2D, and the Convair Tradewind all used the XT-40, I think, Gary. I suppose they are still there, but there was one, maybe two of the XT-40's at the Hiller Museum, I think Stan Hiller told me they were used on the X-18. Pratt and Whitney had trouble on their hands with the engines in the C-133, too. according to what I heard. One C-133 pilot told me on long flights they sometimes carried a spare.