Part No. STC50081
is the Land Rover Harness for the 7 pin electrics 'N' type. Very simple to install, just plug and play
Part No. STC50389
is the Harness for the split charge system 'S' type
Of course you can buy generic parts but they wont flash the tell tale on the dash without a bit of work.
I found over the years with previous motors, if you use generic stuff with scotchlok connectors or similar, over time the electrics don't work properly.
On my TD5 I bought the above N type harness and once fitted was able to forget about it, never had any problems with it.