289 crank pulley bolts needed
 

I need to know the size of the 3 bolts and the thread so I can get new ones from the local hardware store. I do not have the originals.

3/8 NC I believe.

Ok, the head is 3/8, but what about thread size (I understand that they are not always the same). How deep/long should it be? Thanks.

3/8 x ~ 1 bolt.

Add the thickness of all parts and locking devices and add 1.5 times the bolt diameter which happens to be 9/16 for a 3/8 bolt. This yields the needed bolt length.

The bolts in my C ballencer are 3/8 x 1 NC with a 7/16 head and integral washer. 3/8 usually have 9/16 heads.