Tranny Problems

Ive got a 170K miles on my 97XJ auto tranny on my way home from a 4hour road trip yesterday i felt the tranny slip when i came to a complete stop and accelerated the rpm shot up and the i slowly moved forward plus it wouldnt shift, ill be doing 70-75MPH with the RPM at 3k... I changed the fluid maybe 30K miles ago.. Is this a sighn my tranny is going? if so..
Better to rebuild or pull a tranny from a wrecked XJ ?

Are you sure you don't just have a leak?

I would have noticed a leak