I have the 4L60E in my Tahoe and just hit 165,000 miles. The trans works awesome. I got the tahoe at 130,000 too. It sat for 5 years before I got it. No idea if it has been fixed up or not. As far as mileage, I have the 5.7 and it gets 15-18 MPG. Not the best, but pretty much the average for an...