I have a complete replacement option for you, but there are no replacement round spring bars for your Curt round bar weight distribution hitch that are rated for the 500lb tongue weight of your trailer. Since your current spring bars are rated for up to 1,200lbs of tongue weight you will have a very very stiff ride so I do not recommend using them.
To get a system that is rated for your tongue weight range I recommend looking at the Fastway e2 Weight Distribution w/ 2-Point Sway Control... view full answer...