stock 3.07 gears - how low can I go?

[GMC-YA68]

My truck has factory 3.07s. Factory D44/12B. With my LS swap which consists of the overdrive tranny, the overdrive gear and my tire combo will be basically worthless unless I plan on cruising at about 90mph! How low of gears can I swap to with these axle housings? I'd like to end up with 4:10/4:11 --whatever. I have read about series 3 and series 4 carriers but having a hard time understanding what is actually what.

My truck is a 72, non-posi rear end.

[Chulisohombre]

Depends on what tire size you want to end up Using. 33-35 inch tire with od I'd go with 4.56 gears. Stock tires 4.10. 37-40 inch tires 4.88 gears. But really any tire bigger than a 35 and your 1/2 ton axels won't survive long. From your pics looks like you have 33s. So I'd go 4.10 if so.

[GMC-YA68]

You are correct, I am running 33s. I'd like to at least run 4:10s but I have heard/read/searched that the carrier won't accept them. Then a thin or thick cut gear comes into play. Any gearing gurus want to chime in?

[Chulisohombre]

I think the gear break on carrier is 3.73 and up. So would need a new carrier in probably both axles. Or put in a limited slip or locker at the same time. I'd love to have a arb in mine. Money was tight when I did mine though. My trucks always been on a limited budget.just looked it up. Confirmed 3.73 is the gear break on both axles. http://www.crawlpedia.com/thick_gears.htm

[hemi43]

I'm doing the exact same swap on my Blazer, and have calculated 4:10 gears to be perfect.
Thick ring gears are available for both the Dana 44 as well as the GM truck 12 bolt so you will not have to replace the carrier.

[Chulisohombre]

That's always a option too. I looked they are selling for about 160. A lot more if you need to pay someone to set them up. I've done it a couple times. Just takes slot of patience.