Well, now @
tofurun ........ you REALLY messed up this time .........
First off, you replaced a TWO piece driveshaft with a ONE piece driveshaft. So, when it cools and contracts, it PULLS on the gears of the transmission apart, thus when they are started up they SLAM together, causing that KNOCK.
Of course this sends a SHOCK through the drivetrain, which is transferred to the differential and will eventually knock a tooth off of the ring gear.
In addition, the SHOCK wave will be transmitted through the shafts in the transmission into the clutch assembly and will, in time, put the pressure plate out of balance and not only scar the flywheel, but will BLOW up the clutch disk and FREEZE the throw out bearing.
Next, you will hear the dreaded "neutral rollover" ask @
Ultramaroon for details, which is nothing more than the inability of motul gear oil to deal with the shock waves ....... leaving the gears and bearings to grind themselves to oblivion.
I'm sorry for your impending disaster .......
humfrz