One thing is for sure... your turbo is blown. Before you go too far, you need find out if the rods are bent.
First thing, charge up the battery.,
Remove the intake pipe to the Manifold and pull the glow plugs. Unscrew the injector harness plug so it does not fuel the engine. Plug the turbo oil line at the oil filter housing. I believe it is a 12 x 1.5 bolt size. This way, you can avoid dumping more oil into your intake and it doesn't matter if you remove the turbo; it won't make a mess all over the place. Run the engine, no glow plugs. Make sure that you don't have anything in front of the car that you don't want doused with oil. You might blanket what ejects from the gp holes.
Once you get the majority of oil out of the cylinders, test cylinders with a compression tester. The Horrible Freight ones will work, as long as you replace the schrader valve. With as many bicycles as the Chinese have, you'd think they could make a schrader valve...
DO NOT OVERTIGHTEN the 10 x 1.0 gp adapter. Snug is all it needs to be. Attach the test gauge. Check compression for each cylinder.
If you are strangely lucky, which this is a case where that can happen, you will find the cylinder pressures even. Anything between 460psi to 500psi, with no more than 10% deviation is good. Footnote: Compression on a diesel is performed by running the engine until the gauge will go no higher.
If you are very lucky, you will need to replace the turbo and remove the piping from the turbo all the way to the intake manifold (The intake manifold has to come off anyway, so do that and the turbo comes out the top). Make sure any of the exploded turbo blades, which is very likely, are removed from all the piping, manifold and the intercooler is completely washed out.
If the sad event is that you show the most likely #2 or #3 cylinders with lowered compression, the cylinder head comes off and you drop the oil pan. Measure heights of the pistons. Most common example for a 2-hole head gasket: Pisont projection should be .039"-.043". Pull pairs of reciprocating pistons to match weight and length of replacement piston/rod sets.
We are expert at reconditioning cylinder heads and have good used rods, pistons and whatever you might need for assembly. Let us know if we can be any service.
What turbo can you get for $500? We suggest new and Garrett for best bang for the buck. We know there are rebuilders of turbos, but they are unfortunately, few and far between. A takeoff may be as bad as the one you are replacing and poor rebuilds abound. New at that price? Doubtful.