When I did mine I used Northern, they had it all, but I had to go with a non galv axle also. I painted a few coats of trailer cote or something like that paint.
after 3 years in the salt I had just a small spot of rust that I cleaned up and repainted. I sold the trailer some time later as my roller shafts were welded in place on this old Caulkin's trailer, and there were no parts for it anymore.
Just take a hammer and tap the whole frame before you get going!! tops sides and most important the bottom!!
A grinder & sawzall They are your friends!!
