RottenMutt

The positive cross-over cable between the two batteries is as important as the ground cable, this was causing my latest torque converter thrashing. Some stupid engineer thought it would be wise to send the most critical engine sensor grounds to the RH battery ground terminal. If you have any problems with that positive cable, then the electrical path will have to route thru chassis ground or engine ground to get to the driver side battery ground. I spit open the existing lead battery terminals and replaced them with marine battery terminal top posts and selterm marine grade terminals lugs.

I'm an original owner of 1999 block 53, hasn't cracked with only about 135K miles on motor. But i never received anything on this... fillet is a stress concentration, poor design... https://topclassactions.com/lawsuit-settlements/lawsuit-news/2994-dodge-ram-cummins-diesel-block-class-action-settlement/

Less timing can result in boost creep.

what are your exhaust temps at 65 mph cruse? i'm thinking late injection timing?

fastest thing is to check is the ground wire that goes to the passenger battery from the harness from behind the alternator, check the splice connector, wire to battery terminal, check the positive crossover cable by checking for a voltage drop from positive battery post to positive post (should be zero voltage), and clean the battery terminal(s). are your diodes good in alternator? if none of that fixes it then do W-T mod, even if it fixes it consider doing the mod.

+1 on grey connector that goes to the passenger battery ground post. eliminate it with soldered on round lugs and put a bolt and nut on it to make the connection. Also watch ALL the lead battery terminals (positive and negative) to the battery cables, they are the culprit as well. re-crimp with 2.5 lb sledge and anvil or replace.