Outer Limits 4x4 Board

i just cut my driveshaft in half on my gq and there was a piece of carboard rolled up in side, just curious to know if this is normal and what purpose it has?

yes it's normal

helps with the balancing I believe

the early holdens come out with them and alot of different model trucks, has do do with the harmonics of the ts and keeps them quiet.

yes it stops tube from ringing it has nothing to do with balance, expanding foam does a better job ,aluminium tube is even better as it not a hi tensile material so its not affected by harmonics as much as steel