My Cummins 6B engines have OEM a 8D starting battery for each engine.
The 8D battery has approx 1400 CCA rating (interstate batteries)
My Cummins 6 cyl diesel powered pickup has two group 65 batteries which have 750CCA each as a OEM installation.
My thought is that two different manufacturers opinions of the battery recommendation for a Cummins B series 6 cylinder engine result in 1400-1500 CCA.
I think Iíll stick with their recommendatons.