Upgrading front axle on 2008 Cascadia from 12,000 to 13,200 lbs

My 2008 Cascadia has worn out front springs. They are rated at 6,000 lbs each.

I run flatbed, triaxle (I'm from Canada) and run always heavy. With my fifth wheel all the way back and a heavy load (my last one was 64,500 lbs of lumber) and the 100 gallon tanks half full, I was only 200 lbs under the max weight on my front axle. I'd be 200 lbs over if my fuel tanks were full.

So, with my front springs worn out, I'm wondering how hard is it to put 6,750 lb springs in and have the front axle rerated to 13,200 lbs. Or is the i beam different? I asked my dealer but he wants the VIN and tells me no way to upgrade.

Does anyone know?

If I had heavier front axles, I could install 150 gallon fuel tanks some day.

 

Just following up. I asked a few spring and axle places and they all said that Freightliner has to do the upgrade and note it on the sticker. The dealer told me that I would have to upgrade the whole front axle, not just the springs.