3.89 gear...3 or 4 series carrier?

[ItsA68]

I want to get a 3.89 gear for a 12 bolt car rearend. Plan to get a Trutrac or eaton posi. Which carrier should I get? a 3 series, or a 4 series? The same gear ratio is available for either carrier. It seems like the 4 series carriers use a thicker gear?, or is it the other way around? I remember a spacer if you were using the gear from one series in the other...3 in a 4 carrier, or 4 in a 3 carrier...can't remember.

Are any street series gears better or worse from a brand standpoint? Was looking at US Gear, or maybe Richmond?

Any suggestions are helpful. Good price? Where?

Thanks,

~~fred

[big gear head]

The 3 series will give you more options if you decise to change gears later. The 3 series uses the thick gear. I like US Gear.