1975 diesel smokin rattlin hard starting
 

Just changed the starter, had previously put in a new pump and it was set to 0 btdc, the book said 24 btdc, changed it to that and everything went nasty.

any suggestions??

Sounds like something is very wrong with your timing. Very extreme timing chain stretch maybe?

Check all timing related items like put crank at tdc and check cam for timing, then make sure the pump is in there right at 24. Check for chaing stretch.
I beleive it is #1 and #4 that fire at only 4 degrees of movement and a little off on the timing can make a huge difference on the car and the way it runs.

Sorry I have no magic fix other than to say back up to where it was when running good then go through the steps you took when changing things. One of these must have caused the problem.

I'm also guessing it is a 300D...

One other thought occured.
Could you have missed putting a vacuum line back in place. I'm not sure what car this is but on some IPs there are vacuum lines on the IP that can affect timing too.

If it is a pneutmatic governor the back line does this but you ould know if it was loose becasue the motor would run away if it was loose. Ask me how I know...;)