Someone makes a coolant that is supposed to function more efficiently than others, don't know the name, or if it is approved by Cummins.
If if were me, I'd focus on installing better sound-deadening insulation beneath the floor and dog-house engine cover.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy