'93 PAU cradle bolt washers rusted out

[Wrightjsjj]

There are six bolt/washer/insulator assemblies that attach the cradle to the frame - two in the front and four in the back. All four rear bolt washers failed due to corrosion (car has spent it's entire life in the Chicago area) and the rear portion of the cradle was hanging low. All four bolts were still intact. However, when we tried to loosen the bolts, the two nuts (which I assume are welded to the frame) for the outer rear bolts broke loose making it impossible to remove the bolts. We were able to remove the two inner bolts, and reinstalled with new washer/insulator assemblies. So, the cradle is being supported by four bolts (one at each corner) instead of six. First question: Can those two nuts for the rear outer bolts be replaced and how do I get to them? Second question: Do I really need six bolts or can I get by with four?
Thanks for any help!

[wrightz28]

I'm sure the General put 6 bolts on there for a reason.

[Wrightjsjj]

Yes, the General did install them for a reason, but what is the reason? Is it structurally necessary, or is it just to reduce vibration/noise? The mechanic at the Buick dealer thought I would be fine with just the four. I was just wondering if anyone else had any experience with this. I would be happy to replace the missing bolts but it appears that it will require cutting holes in the floor to access the nuts. Again, if anyone has any experience with this I would be very interested to hear from them.