I have a 2003 f150 Lowered 3/4 properlly, 4.10 gearing, diablo tuned chip, bilsteins, k & n air filter, throttle body, and only 3000 miles. i recently noticed a leak and brought it to ford. they said that since my car was lowered it was putting to much pressure on the transmission seal and leaking. they ( airport marina ford, Los Angeles) told me to cut the drive shaft 3/4 inch. Did that and put it in and leaked even more. Brought it back and they said it was cut to much. so they sold me a new drive shaft and i had it cut again and this time it didn't even fit. It was the wrong shaft. Stupid me for not checking first. But my question is with a 3/4 drop do you need to cut the shaft, and if so how do you measure it and what should i do about ford telling me something and now saying they didn't say anything.

 

I lowered mine 5-6 and didn't need to shorten the driveshaft and I shorten driveshafts for a living. If, in your instance, the lowereing did, in fact, move the rear end forward (quite common) I would think that shortening it 3/4" would never be too much.

My guess is that when you drove it with it too long (if it was too long) you might have damaged the soft bushing in the tailshaft.

To check it, lift the truck, release the parking brake, put it in neutral and then see if there is any side to side or up and down movement of the yoke in the trans. The running clearance is only about .005" so it shouldn't move very much.

If you determine the bushing is shot, some trans shops have a special tool that will R & R the bushing without even removing the housing. New seal, of course, too.