03 GTP, 128k mi.

Had the car almost a yr. DD & project. Ran iffy when I bought it, & handled much worse - super soft & sloppy. Relaced almost everything on front & now have vibration on acceloration.

I am suspecting differential more and more.

So seriously considering paying for professional diagnosis. What can I expect? Is there equip that can give definative diagnosis of tranny malfunction?

Thanks in advance