The recirculating ball argument as an excuse for why the Grenadier feels like it does is just ludicrous.

My stock suspension IG is at ~2.3 caster. On a glass smooth, flat piece of hwy asphalt (a rarity here in LA), my IG drives perfectly straight. On anything but (e.g. I-10 heart of LA), I'm usually holding the wheel 5-10 degrees to the right to go straight. On my IFS Bronco Raptor which comes with 37s bone stock, it tracks dead straight with steering wheel centered on same piece of tarmac with minimal correction compared to the IG.
It's just the nature of the beast that I've come to accept. It's an agro farm truck, no equivocation.
The fully returning steer to center is an absolute nonfactor. Enjoy!