A friend was doing an underdrive pulley swap on his truck and had the pulley bolt break off inside the crank, used an easy out to pull out the bolt but now has to rethread the inside of the crank. What size would it be? I've never heard of something like this, i thought it only happened with head studs

 

I've seen it happen before (here) but don't recall the solution. bump TTT.

 

Longer crankshaft pulley bolt, M16 x 2.0 pitch x 120mm long
Thats the specs of a long crankshaft bolt, used to make installing the balancer easier.

 

heli-coil it . . . and get a crank pin kit, and hope that it holds