My 05 SCab has the driveshaft clunk everytime I take off from a stop, I purchased a can of the telflon grease used to lubricate it & marked the front of the slip yoke to line up when I reinstalled, my mark rubbed off somehow and cant tell exactly where to line it up, if they dont line up, will I have a driveline vibration? Or can the splines on the slip yoke only line up in one spot as I noticed there is one spot where there is a gap in one spot with about 3 splines missing, (blind splines I believe they are called) is this to align it? Not sure what to do now that I have no way of knowing how the slip yoke was previously lined up to the male end coming out of the trans.

 

You might, but the alignment is more critical at the rear axle. I would reinstall the d/s, mark it once installed. If you do have some vibration, re-index the d/s 180 degrees and re-evaluate. It'll be more trial and error, but I don't see you having any issues if it's not in the exact spot as before..

 

While I cant speak personally about the F-150, most, if not all, drive shafts will only line up one way.

 

If the yoke has numerous amount of splines, yes you will need to re-install the driveshaft the same way it came off. This is called phazing. The u-joint need to be in phase or else driveshaft will not rotate smoothly, giving you a vibration.

 

Maybe I got lucky but I just aligned the bolt holes up to the rear end and moved the slip yoke a spline forward or back til it matched the best. No vibration. Doesn't seem to bind. Been driving it for 20k+ now.