From 76' 300D non-turbo -> turbo (problems??)
 

I have an 81' 300SD, bad block. Replacing with 76' 300D, wanting
to install turbo from 81' on the 76', can this be done with out
modifications? if not, what would be the recommended changes.
can someone help?:)

In short, No. If you want to melt the engine in 100 miles, yes.

The turbo has things like oil cooler, piston oil cooling jets, slightly higher compression ratio, turbo oil line, turbo drain tube, better exhaust valves, and many other details.

The only true method is to just replace it with another OM617.95x engine.
Do a search on this subject and you can find losts of information about turboing an NA engine.