I'm really torn between replacing just the screen and regulator or going for the egr and oil cooler upgrade. My wallet says to just fix what's broken at the moment...
Which gaskets should be replaced when I put it back together? None of them look damaged, but are any of them required to be replaced each time?

 

Best to get a turbo hardware Kit and replace the gaskets and bolts

Mainly the the gasket on the Oil supply line on top of the turbo must be replaced it has a little crush/seal factor

The intake gaskets canbe reused

Now the Oil cooler housing gasket IDK most folks replace that oil cooler and all gaskets if there in that deep it all comes in an oil cooler rebuild kit but if the gasket looks OK you may be able to just throw it back in

Also dump alittle oil in the HPO reservoir then install the cooler it will cut down the Long crank time when you go to start it

Make shure you put anti seize on those turbo bolts and the Flanges on the marmon clamps trust me it helps