I make mine
however you can contact your trailer manufacturer or local trailer parts store
I would go to the local steel yard, around here they are called Pacific Steel and Recycling Good company to deal with.
Had a swing tongue added to my trailer last year....dropped it off at the local welder by my lake and they welded one one for a maybe $250. My trailer is the larger sized frame as well so took a while to get the actual swing tongue mechanism from his parts supplier in that size for some reason. They painted it to match and looks like the trailer was ordered that way.
SORRY GUYS!!! My last post was meant for a different thread....
I would go to your local steel supplier and buy a piece of 3x3x 3/16” steel tubing the length you need. Many steel suppliers will sell 10’ material even though standard lengths are 20’.
it won’t be galvanized so you will have to paint it. Around here, we have a place that can hot dip galvanize steel.