I have had to replace both axles on mine in the 13 years we have owned it. First axle lost its' camber. I bent the second axle by hitting a post in a gas station. Original axles were 5200 pound axles. Should have carried my 5'er fine based on it's weight. When I replaced I went with 6k axles, they look the same but have thicker walls and give a little extra carrying capacity. Was on the road when I had the last issue. Shop doing the work in Fla. was quoted 14 days for deliverer of new axle. (Most axles for trailers are not off the shelf items but built with measurements for your specific trailer.) Called Croft Trailer in Kansas City, Mo. Besides other trailer work they fabricate and ship axles all over the country. With the measurements from the local Fla. shop they built and shipped the axle. 4 days later it was installed and we were back on the road. $384 for the new axle, $267 for the removal and install. Shipping was right at $100 IIRC.
2009 Ram 2500