Yamaha F150TXR Need Help Identify Bolt Rust what to do?

[beantownace]

Hello all,

I have a 2006 Yamaha F150TXR and there are two like bolt heads that are completely corroded. Wondering if this looks like a bolt head or a corroded nut etc. Any suggestions would be a big help. Not sure if I should just chip it all away and then I need to figure out what size etc. to replace them. Attached a few picks of the bolt on the lower mount inside.

 

[Tegweni]

M16 or M20 nut replace coat the new ones with a good 2pack paint.