Should be a new SCAT 428 crank. That is what they have on the build sheet along with a 4.13 bore and 3.98 stroke. I have a 66 block C6ME and the "A" an the back so I took thier word for it at the time. I have not looked at the crank for identification numbers only the block, but I did see a picture of a new SCAT 428 crank with the half-moon at mustangsandfords.com after you asked.
http://mustangandfords.com/techartic...nd_sb2_k_z.jpg
Anyway, after many thrashings and a good amount of track time, the engine performs as billed.
--Mike