I've got an 06 600 (non-sno pro) I have not had an issue with the tunnel, over 4200 backwoods miles. I thought the "sno pro" was the one with the weaker tunnel? Nonetheless, no issues for me. As stated above, keep the diamond drive fresh with a flush & fill every season. As time goes, you may find little things to do to it to tweak the sled for your riding style. I love the backwoods, so I added an 09 adjustable steering post with mountain bars, parabolic ski's, extended the rails to 144 & put on a 2" paddle. The key to any good sled is regular & timely maintenance. This is the best sled I've had, even though I would like something "New", I can't justify the $12 - $13G's. You won't go wrong with your choice, enjoy.-Mezz