We would need more information to make a call on that.
What is your tow vehicle?
If you have a 1-Ton Dually, you probably need 500 lb bars. If you have a half ton pickup, you probably use 1000 bars. The stiffer the suspension of the tow vehicle, the less stiff you need the trunnion bars.
Think fishing poles.....the bars need to flex to work. You have more play in a limber rod than you do with a stiff one. If the suspension is stiff, you need a limber rod, if the suspension is weak, you need a stiffer rod.
I am pretty sure Inland Andy would concur, and he is an expert in such matters.