[slowmover]

I'd love to see 1600 at 60-mph for solo!

As is, the NV5600 6-speed man trans with stock tire size and standard 3.73 gearing I see 1625-rpm at 54-mph on the city freeways here in Fort Worth. (RPM is from Ultragauge OBD reader).

These trucks are set up to run and "work" 55-65/mph maximum, IMO.

As per the Dodge Owners Manual I've always used First to get it rolling. The shift to Second is almost instantaneous. (Normal rate of acceleration for one of these is best described as ponderous: it's a medium duty synchro trans behind a medium duty engine. Design life is far longer than the V8 diesel drivetrains, and this is part of the tradeoff). So when I've considered the 3.42 swap it was in the knowledge that I'd have to stay in the lower gears longer, and to a higher rpm before shifting to bring it back in above peak torque. Especially when loaded. (I've also used these trucks on the oilfield hauling 20k+ trailer and load; but in 4.11/DRW configuration ).

But these HPCR Cummins trucks are already overpowered straight from the factory for their intended use. So the "compromised gearing" vis-a-vis a decent load is more about better skills at the wheel to get up and go. Into traffic, across highways (I already avoid left hand turns solo, and REALLY hate them when with my trailer and stretched out to 63'; the trailer momentarily stops across all lanes in a left while it pivots; why trip planning is an FE requirement for working trucks, not optional), and down the highway entrance ramp. May take well over a mile to reach cruising speed.

So, FWIW, I spent nearly all this past year entering highways in my work truck at anywhere from 25-40/mph. It's just not a concern given some ability to read mirrors and interpret. It's why we have a wide differential between lower and upper speed limits.

For what the OP and I both want (I'll state it as better, full-er use of each gear plus a relatively low top end speed while working; relative to the moronic masses travel speed), it's a win. It'll take some adjustment as I've been driving this pickup about ten years now. I've wanted to do this gear change for several years but it's still not at the top of my long list.

I know I'll be in Direct more often, but Overdrive isn't a "strong" gear in the first place. Downshifting more often is a penalty offset by better flatland and solo MPG. Granted that as a commercial driver I don't give much thought to having to shift more often. Nor do I spend any time anymore in trying to improve MPG as the percentage gain on a stock truck is too small beyond my current efforts (I've experimented), so I know I'm ready for truck specification changes.

And those experiments in driving technique show me that I'll willingly (I hope it's also happily) compromise heaviest load towing ability as my truck and travel trailer are considered by me to be a matched pair. Their combined weight is less than those oilfield loads. Thus, not hard work for a Cummins.

I'm looking forward to what the OP has to say about the camshaft change with this gearing. (And as a note I can't always sign in depending where I am, but I always read the posts/threads).

Any plans for a data reader so to re-program on a custom basis?

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