Scat stock replacement small block chevy 400 CID 70-80 years, cast steel material, External balanced 3.750″ stroke. Standard weight at 50 lbs. Rod journal diameter 2.100″ mains 2.649″ diameter . Must use 5.700″ length rods . 2-PC rear main seal, needs balanced before put in to service. Special order 3-5 business days. Please e-mail with questions.