Okay, for the benefit of anyone searching for this in the future...
I have a Series 3, which was fitted with a 2.5n/a defender engine (12j). I bought a defender 300tdi engine to replace it.
First i swapped the clutch plates, so i had the plate i was running originally (the spines were different- Series has less splines).
I didnt swap the flywheel housing, i just cut the lugs of the bottom.
There are 3 bolts on the housing, where the gearbox bellhouse mates which do not line up (3 at the bottom)
I used the std series engine mount on pass side,
I modified the drives side mount - quite easy tbh. the 300tdi mount is about 8 inches further back
I swan necked the exhaust manifold right at the top to miss the engine mount
i used std 300tdi rad, and mounted the intercooler above engine (i will replace it for a bigger and thinner one with fan at a later date)
I used all the 300tdi pipework, just cut bits shorter etc
The 300tdi engine i bought, didnt have the viscous fan, it just had a crappy broken leccy one, which i replaced with a bigger, stronger version from a honda.
i wired the fuel solenoid to come on with the ignition
i used the std series throttle link, and extended the rod by 70mm
i think thats about it, i cant think of anything else....
It took me 3 evenings to do it, i had a little help.
You will need a welder, lifting gear (i used a fork truck), basic hand tools and loads of degreaser is always useful! As is wd40.
Its quite straight forward and easy imo...
Thanks
Shabs