06 GS300 Transmission and Mileage

[TheSpurge1689]

Hi I’m wondering if you guys and gals might be able to help me out. My wife’s grandma has an 06 GS300 with 228,000 miles on it. I think her transmission just went out. She was pulling into the garage, thankfully, and her a loud noise, which she assumed she hit something and the car stopped. 

There aren’t any warning lights displaying and it turns over just fine. When you shift it out of park it sounds like it changes into the appropriate gear, reverse or drive, but won’t move. However, it will go into neutral.

Does anyone have an idea what might be wrong? If it is the whole transmission what does a replacement repair typically cost? And lastly at 228,000 miles is it typically worth fixing at that point? She’s concerned that she will fix it and then something more expensive will need to be replaced. I’m under the impression that typically you can get a GS300 to run over 300k easily. Is this an accurate assumption? 

Thanks in advance for any assistance you might offer.