Disco 2 Crossmember bolts !!

Any advice for removing the cross member bolts...
Need to replace these bolts, as they are just rusted solid. I have used penetrating oil, and heat but they still wont budge. Two have snapped off, after using a reverse spiral extractor. Will neet to remove the captive nuts after as well, as I have stainless steel serrated flanged nuts, and 20mm stainless hex bolts to replace them.

I take it its going to be brute force and chisel off the bolts and heads then ?

I would continue with the Irwins - either they will slacken or shear. Then chisel the captive nuts. Not the easiest job in the book!

I suspected it was going to be the case... how easy are the nuts to shear off, anyone done it before. I have an air chisel, but there's limited space to use it...

Will depend on the strength of the rust!! The ones on my new chassis were barely attached and most freed themselves when bolting up
Like you, I replaced most with serrated flanged nuts.

what is the bolt size? I noticed 2 of mine are missing but luckily not sheared off. Ta.

8mm x 20mm

New bolts fitted... Drilled out the old bolts with a 6mm drill bit, but even with a reverse screw bit, they wouldn't budge. So I inserted a blunt ended round chisel, with a 4mm end, and gave the nuts a few good taps. Off they popped. They are welded only in each corner, so came away pretty easily. Tapped out the old nuts, and then fitted the new stainless steel flanged nuts, 8mm washers, and allen bolts. All done... Just the centre crossmember to do next...

Two more... probably didnt need to drill them, but it made it easier to locate the punch.