You indeed want to have the new motor mounts and the transmission mount in place before you start connecting up the flex discs and the centre propshaft bearing...

...however I think the better order of torquing / tightening is first the flex disc bolts and the mount for the centre bearing on the propshaft. Leave the large nut on the propshaft loose.

Next wiggle the engine and the transmission into a preferred position. Make sure it is sitting correctly in the centre of the vehicle - it is possible to make the engine and the transmission sit askew. If you look at the transmission mount resting on the transmission mount cross member you can see if the small M8 bolt holes are aligned correctly with the slots in the cross member. Once you are sure it is all good tighten the motor mounts and then fit the bolts to the transmission mount.

It is then best to put the car on its wheels and push it around a bit (transmission in neutral!) - backwards and forwards - so the flex discs find their best position and the propshaft splines find their preferred place. With the weight still on the wheels tighten the big nut on the propshaft.

I know this is all a pain in the arse but it reduces the chances of drive line vibration problems.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!