I just did this recently too. Cracked right where the parting line is for the casting. Thought I'd be all slick and use my new torque wrenches. Whooops.
I only had it at 20 ft-lb too so I could sneak upto 31.
Ended up buying a new pan since the crack was large and the threads on the pan sheared right off. Gutentight was the previous method that I will be going back to.