2002 Highlander LTD Whining around 40mph

Hi all, New to the site but a long time fan. We have a 2002 Highlander with about 112k miles and started getting some high pitched noises coming from the rear a couple of months ago. Now, it whines even louder around 40mph. Definitely noticing diff oil drip spots in my driveway, and wondering if a new seal would fix this or is the whole rear diff in disrepair? Apologies for the dumb question and any assistance and advice would be greatly appreciated!

If you see the drips and hear the whine, that means enough oil has leaked from the diff to starve the gears and bearings of lubrication. Get the level checked right away. A pinion seal and gasket will be needed to stop the leak and allow the mechanic to determine if your diff is damaged from the lack of lube thatbwill require extensive repair.

Thanks Mustangman! I’m going to give my mechanic a call and see if I can bring the car to look at the parts you mentioned. It sounds like it could be past the point of no return though. Appreciate the advice and I’ll keep the forum posted in case someone else runs into this problem down the road.