What is this worth? 1999 Jeep Grand Cherokee Limited

A grand is more than I would pay for that vehicle.

"Has 165K on the clock".

It has 165K on everything, not just the odometer. Depending on how it was maintained, there's a lot of crap that can go wrong on a 165K vehicle, and even more on a 4WD vehicle (especially one with a blown engine at only 165K).

I'd offer $500.00, possibly $600.00. If he's not willing to deal, I'd walk away without looking back.