That noise is either a slipped liner or it is a bad main bearing.

If it is a bad main bearing or rod bearing, don't drive it as it will throw a rod and put a hole in the oil pan or the block.

If it is a liner - the way you tell is -

If it is quiet in the first three minutes when you start it and then after driving a mile
this sound comes - then it is a liner slipped and thrashing up and down.

Solutions:

1) If a liner - PIN the liner with a screw into the block.
2) If it is a bad rod or main bearing - replace all the bearing shells and that will solve it.

You may have a scored crank shaft now - and if that is the case - whole rebuild.

A 2003 engine does have slipped liner problems - so cut your losses.

Fold the cards.

 

Don't put money into it.
Get a used LR3 or LR4