You need the 200tdi engine mounts, an extra earthing lead (the 300 earths to the passenger side engine mount), and a 200tdi exhaust, and the 200tdi radiator & intercooler, and a 300tdi temperature sender
- You need to remove the passenger-side engine mount, and weld the 200tdi mounts to your chassis
- You can ditch much of the 300tdi wiring, just use the connections you need to the components you need.
- Note: the 200 temperature sender does not work at all with the 300 gauge - drill & tap a 200 sender to accept a 300 sender unit (make sure you cut this sleeve right down, so that the 300 sender unit sits fully in the thermostat housing)
- You need to swap to the 200 radiator, hoses, intercooler & air-cleaner... and you'll need a wee length of pipe to extend the hose to the expansion-tank
- the 300 exhaust system doesn't fit at all, so you need to replace it with a 200 system
The gearbox mates just fine, that's not a problem.
You'll discover that the revs read a wee bit low, but other than that, mine has been fine for 16-18 months :)