Gary -

I've done Corkscrew several times, and will be doing it again next Wednesday. Using the "standard" route, there's no class 3, not even close. I have a GPS track of it on Wikiloc here, and it contains a brief description of the hike.

BobR has several other routes, some of which may be class 3, but have not taken any of them. Let me know if you have any questions.