What would make the rocker arm break on a Durango. If all I was getting done was an oil change? can over filling cause pressure to break the arm?

After only 160K the body bushings need replacement, no rough road driving, cost estimate given around 450 USD. That sounds a lot or am I mistaken.

Ticking sound (sounds like baseball card on a bike spokes) from the right side of the engine at start up. It increases with acceleration and diminishes after engine is warm. The sound can be heard when car is idle,but low. The car mileage is around 16K miles only and I have been doing the regular service at the dealer's workshop. I hope it is not serious.