By admin / Cummins ISX / buying guide • Cummins ISX • engine assembly / 0 Comments 2 Nov Cummins ISX Engine Assembly Price: A Buyer’s Guide to Configurations and Cost Factors The Cummins ISX is a heavy-duty diesel platform produced in two primary displacements: the ISX15 at 14.9 liters and the ISX12 at 11.9 liters.