He’s got 4.88s with the 40s and has commented on how much happier the engine is with the 40s vs the 38s.
Calculator says I would be at 2040 with 4.56 and 1834 with 4.10 which is what I have now, when I move to 37s. Calc gives my 33s and 4.10s 2,015 rpm so almost seems like if I stay with 4.10s and go to 37s, I will have the same net effect as David’s 38s to 40s with 4.88s.
If I remember correctly, the engine seemed pretty happy with my worn out military 37s. I remember being relatively impressed with the truck's ability to move down the road on the trip home after purchase.
So perhaps the best thing to do is stick with the 4.10s. I guess I was thinking since I have to regear the 60 anyways, now might be the best time to gear to 4.56 or 4.88. But I suppose it makes more sense to build for what I actually do, instead of what I might do. I guess if I ever do find that I need a lower gear ratio, they aren’t that expensive so it won’t hurt to do it again.