What is the average labor price to replace the Flex Plate?

Our labor rate guides don't have listings that far back. The furthest I can go back is a '76 model, but the '74 and newer Mustangs were a totally different car with smaller engines. Unless the shop has a "Flat Rate Guide" that goes back to '71 models, they may have to go by time and material. A typical labor time for other models like the Granada were around five hours. Expect the Mustang and the larger engine and transmission to add to the difficulty. My best guess would be around 7 - 8 hours plus the cost of parts. If the people at the shop can give you a more definitive estimate, let me know how close I came with my guess.