Welcome. The LR3 is an amazing vehicle. Spend some time reading on this forum and you'll learn all about your vehicle and what to keep an eye out for.
First off, OEM stands for original equipment manufacturer. Essentially, all the parts that came on the car when new and all the parts purchased from the dealership as replacement for the original parts are OEM. They are made to the manufacturer's specs. The parts that are not OEM and made by other companies are usually referred to as aftermarket.
If you haven't already, change the front and rear diff fluids. A lot of the earlier LR3s suffered diff problems. You can read about it on here. Diff fluid is cheap and a good preventative measure. The costly result of contaminated diff fluid could cost you thousands.
If your vehicle sags after sitting overnight, check the air suspension. Leaky airbags or valve blocks can cause your air compressor to run overtime and burn up. That could be a $600+ mistake.
Just spend some time reading on here and you'll know what to look for in no time.
Colin
