main seal parts list?
 

I'm trying to get a good idea of what i should replace while i have the engine apart for my rear main seal. i'm getting new motor mounts/shocks and replacing gaskets related to turbo. i was wondering if it would be a good idea to replace the bearings while the crank was exposed or if it would lead to big problems. i'm looking to keep this under $500 in parts and am at $130 after mounts/shocks and the gaskets i talked about above.

When you reassemble the engine you should ideally check the clearance of the bearings with plasti-gauge (or en equivalent).

However,

Is the crankshaft scored?

Are there and wear / damage marks on the existing bearings?

Have you mixed them up?

Did you measure the end float of the crank before you took it to pieces?

i havent started and wont tell it warms up. i'm trying to extend my engine for as long as i can. i'll be in the middle of farming when i start the project, so i was hoping to be able to have the parts ready to go. i do have another crank that i could have a shop check and by bearings for. would it be to much work to just replace the crack compared to a rebuild? my engine has quite a knock that comes and goes based off the weather, rpms, how long its been sitting, and if i have done any injector work on it. no one can tell me whats up with it. over 10k miles on it from the day i bought it with a injector knock that got worse, then better, then worse, then gone for 250 miles and then came and went based on random things. its gone and at anything above 2500 rpms and worse at 1500 rpms. i saw a video on youtube with the same noise, but the dudes cam went out on it one day.

sounded like this when i first bought it.
Ticking sound on a 1982 Mercedes-Benz 300 D Turbo - YouTube

this is what it sounds like now but a little louder at times. not my vidoes btw and i left the car back at my parents house so i cant record the noise.
85 300D Mercedes engine knock - YouTube

Benzdude42 - I'm confused - is your engine in pieces or not?

If you haven't taken it to bits yet you should ideally start by reading through the FSM to get an idea of what is involved.

Don't pull the motor apart unless the rear main IS ACTUALLY LEAKING.

If you're pulling it for preventative maintenance you money is better spent on a timing chain and injectors.

Your knock is probably an injector that needs servicing. You can send them out to be cleaned & balanced it's under $100. Greazzer and some otheres do the injector service

its the main seal. the car sat for over 5 years with out being driven and only started leaking after being driven for little over 300 miles. the leak gets bigger over time and only comes from the back of the engine, not from the value cover.