The best advice you have gotten is to have a mechanic check it out. I know quite a bit about autos and yet when I bought my last RV I paid the $250 and had both the chassis and house inspected by a qualified shop. It was the best $250 I spent. They found a few minor problems which I could negotiate into the purchase or budget to fix later but I knew where any problem lay.
133,000 isn't terminal on a V10 but those miles are also on all the other parts in the chassis and house. A cab AC failure could run $1,000. Shocks, tires, tie rod ends, brakes, ball joints are all possibly worn and may need servicing soon in addition to a transmission.
If you had maintenance records that showed that the trans fluid was changed every 30K and oil was changed regularly, and tune-up was done prior to 100K, and ABS fluid was changed along with antifreeze and other fluids, then it might be worth taking a chance. Without records, assume it all wasn't done and stay away from this unit.
