I replaced 26 crossmembers on a older Trail King sliding axle tilt last winter. They were made a square tube and rusted out. It was quite the job, but it was either fix it or scrap a otherwise good trailer. It's not that hard to replace them, just a lot of work, because the rest of the trailer is built around them. If you are replacing quite a few of them, it is better to just remove the side of the trailer, so you don't have to install the new ones in pieces.
Lol I wondered about that too! Maybe a customer dropped a coil on it? That'll do in an older trailer pretty quick.
I do understand it's labor intensive.. I have a 9 quad 9 I'm redoing.. I took the floor off needle filled cut some cross members before I gave up and started paying
I replaced the 5th wheel last year. A lot of cutting old metal out. Rented a welder and did the whole job for about $1000
I've talked to a few guys over the years that have done it themselves. All of them said first last and only time they would do that job! lol