All I am saying is empirical data will prove or disprove it.

Postulating, imagining, thinking about it, saying it is just a myth, or anything else you want to call it cannot prove or disprove it. Therefore it is just an unsupported argument.

Now argue that point.

 

There's technically no reason to mark it in relation to the output/input flanges.
If you're removing it for something other than rebuilding the propshaft the only reason to mark it is so that if you have a vibration after reinstalling it then you know if it's the propshaft orientation or not. Personally, as I said, I don't worry about it. That's with 35 years of working on Land Rovers.
I'm sure the reason the factory manual says to do it is because those are written for dealers. By telling the mechanic to mark it it's likely to reduce any customer complaints.

 

Thank you Tom.

 

Yea I've got absolutely nothing.

Much appreciated. That makes perfect sense. As I thought it is purely procedure thing and to avoid human error. There is no technical merrit.

 

FWIW I rebuilt both propshafts and mixed up the parts with no vibration when reassembled.

 

Where's the excitement in that?

Tom pretty much hit the nail on the head with his response. It eliminates the component from future complaints from the customer.

 

If you didn't mark them when you took it apart (which is different than marking the flange/propshaft oreintation on removal), how do you know you put them back together mixed up?
You might just be really lucky. lol

 

When I cleaned off some of the oil grime on mine I "discovered" a series of red, green and yellow paint marks that line up with each other on certain suspension and driveline parts. Wasn't tire crayon. Not sure if it was the rejection by inspector 47, or a mechanic with short term memory issues ... where wuz I ???