Cummins ISX Long Block CM871. Reviva engines are a perfect aftermarket choice for diesel engine applications. All engines are made to the exact serial number of the existing engine which drives cost out of and simplifies the install process. Every Reviva engine is machined using state-of-the-art equipment and assembled using precise and repeatable methods. Reviva follows documented lean manufacturing processes and principles to create consistent quality and dependable outcomes. All drop-in engines are Dyno Tested, and all long block engines are SIM tested. All parts used are OE or OE equivalent, as well as OE specified, tested and validated prior to being accepted and approved for use by Reviva.