The shaft isn't likely to LOOK broken as it's hidden inside the tail housing. Those shafts are really beefy and it would take a lot of abuse to break one. Ford has enough trouble with universal joints so I think one of those would break from abuse first. If a universal joint or the tail shaft was broken, the engine would run but the car wouldn't move. The transmission would go into gear and up-shift through all the gears, although you might not feel it, but it would continue coasting internally when you tried to put it in park, and you'd hear a horrendous buzzing noise until the internal rotating members slowed enough for the parking pawl to drop into place. You'd feel the clunk when that happened.
You can check the tail shaft by jacking the rear wheels off the ground, (always support the car solidly on jack stands), then turning the drive shaft by hand. When you turn it one way, one or both rear wheels will turn forward rather easily. When you turn it so the wheels turn backward, it will be noticeably harder to turn because an over-running clutch locks up and you're turning more internal parts.
Saturday, June 21st, 2014 AT 1:57 AM