Anyone have experience with selling 150+ lbs items FBA?

I have been selling a 600 lbs item with FBM for a few months and our average LTL shipping is about $400. Just checked Amazons profitability calculator and they say they will only charge $280 to fulfill my 600lbs item.

Can they actually fulfill a box that weighs 600 lbs? If so I’ll ship a whole container to them.

If anyone has any experience with selling extremely heavy items FBA I would appreciate to hear your experience and how you recommend we package it. Does each item need to be on its own pallet or can it just be two boxes stacked on one pallet?

Cheers!