I gotta agree on the rivets.....the OEM Doo rivets are called piercing rivets...there is only a hole in one of the two parts, then the rivet is smashed into the second part...the mushroomed shape of the rivet and deformation in the second part holds it all together...Great for manufacturing, horrible for repairs. As a result, getting the bulk head removed from the tunnel sucks....or removing any bracket for that matter.
I moved some suspension brackets on my sled for an SC3 retrofit. I got Stainless steel rivets. There are also coated structural steel rivets, like Magnalock and so on. DON'T use the crappy plain steel or aluminum rivets from the hardware store. I sourced rivets from our hardware supplier at my company...but you can check ebay, Grainger, Fastenall, Motion Industries....google it, I am sure you'll find something.
I'd check around for a complete used tunnel, or as someone mentioned a sled witha bad/no motor, tehy come up somewhat often.....ebay, dootalk classifieds, monkeyads.com. Or, part the sled out and buy another....it sucks to have to sell your baby in such a way, but your time is worth something too, and the season is short.
Good luck..
Good luck.