I just got rid of my 1999 TD5. First off, loved the car. Was great!
I had es, all the stuff on it which is defo worth going for.
Thinks to look for in my experience:
usual car stuff. Common td5 probs (oil in loom et etc)
check the ace, if it's around x reg, potential for corrosion of pipes. About £1000 to fix, if they go, you can't drive the car! Check under drivers side door at silver block with pipes running in and out of it. Also check actuator on drivers side in the wheel arch.
Check no warning lights on, I had automatic, had hot warning light come on when I was towing. Could just have been a sensor, but never found out! Check the gear box changes up smoothly and goesnt clunk when it goes into gear, can't comment on manual! Check for rust etc! Check bloody sunroofs don't leak!
I got rid of mine as it had a few things that needed doing and could be bothered sorting and paying for it. As much as I loved the car towards the end I was constantly worried about reliability. Swapped it in for a 2002 d90 in the hope it's simpler and less electronics. Not to pit you off mind, they are great!