you'll be lucky to find a decent TD. They were ****e from new.
If you don't want a 300tdi Though I don't know why you wouldn't Get a 200tdi, 300 is easier and cheaper to fit though.
Stick a 200tdi in. I had a td and now a tdi from a disco. Best option is look for an mot failure on eBay or gumtree etc with bad rot. The tdi engine transforms the defender. If you break the disco ( there's a thread on getting best out of it) you will make money back and have a motor with the power to accelerate up hills. Trust me I live on Malvern hills and I tow 2 tonnes over the top no problems now. With td would be lucky if I could.
300tdi cheaper to buy, i wouldn't of said easier to fit though.
Straight fit no modding exhaust exc that you have with a 200 disco engine Need to weld a front engine mount on and swap the flywheel housing over.
This is in a defender of course.. As the OP didn't state what vehicle it was going in.
If it's a series. Then a 200Di engine conversion is bestest..