I have a 1995 300tdi and want ro fit a tachometer. I have seen 2 possibilities one is a 0-4000 rpm and the other is 0-8000. I would prefer the 0-4000 but arent sure if this is suitable. Any advice would be greatfully recieved. Cheers

Max recommended RPM is 4000.
https://www.lrukforums.com/threads/300-tdi-max-revs.127707/