I replaced the seals on my Air compressor. I am not sure why I did it - I think they were leaking a little.
There is a seal kit.
https://smile.amazon.com/INTERCHANGE..._&dpSrc=detail
I ordered that - and a friend pulled the thing apart and changed them.
I wish I could remember the bits he used - because I know I didn't have the one he needed.
We used locking vise grips to stop the coolant lines.
If you stop by any diesel mechanic - or truck stop - they should be able and willing to show you what you would need to do it. I have had a lot of luck with that.
I hope that helps a bit!