Solid axle swap and gearing question

[skyhighsami]

I have a Dana 44 and 12 bolt out of a K5 that is built front and rear and locked. I also have a NP208 to swap the case that's in there now for a floor shifted 208. My question is on the ring and pinion in these axles. They are 5.38, with me planning on running no bigger than a 37 or 38 should I even consider these or try and find some other axles? What kind of RPM will I be turning with these gears and 37s 38s and 40s? I am wanting to run Toyo Open Country MTs since I've been so satisfied with them in the past. They're only do 37 and 40"

 

[SunlitComet]

they would work well with 37" imo. use this calculator to determine your various rpms.

 

[skyhighsami]

The gearing on 37s with 5.38s will be close to what my Trailblazer SS is. But that motor revs to 6200, the Vortec 5.7 turns to only 4900. That's my only concern. We drove it to TX2K13 and at 75 it was turning 2100 with 32" tires and 3.42s. Ideally I would rather be at 2500. With 37s and 5.38s I think it will be 2700-2800. I'm probably over thinking it. Worst case I could drop in the LQ9 I have

 

[_Dylan_]

Using that calculator you will be at 2500-2600 at 75mph.

I wouldn't put 40s on 3/4ton axles.

 

[skyhighsami]

I think I have decided to just go with a 6" lift adjusted to about 7" and get some 17" Fuel Trophy wheels with 37" Toyo Open Country MT. I was wanting to do a solid axle to keep from regearing the axles and rebuilding the wear items on the IFS. But considering how much my wife still drives it and how much I daily it going solid just didn't seem like the best idea. A couple friends have had solid swapped trucks and IFS lifts with comparable size tires and said by far the IFS rode the best. Since I'm not doing any hard wheeling it should be fine. I'll just gear it 4.88 and let it ride.