Best FDR for 3900

[fat rabbit]

I've begun gathering parts and information for a 3900 swap in my 2010 Impala LT, I picked up a 3900 with around 17000 miles from a police car and now I'm trying to figure out what gearing to swap too.

The plan is to swap in the 3900 and spray a wet shot, I have a sprocket set laying around to make a 3.69 fdr but don't know if that would be to tall for a 3900 with nitrous and I imagine the gas mileage wouldn't be good with my car being my daily driver.

The 3900 I'm swapping in doesn't have the variable intake runners on it currently, though I may add that feature later on down the road. I was originally just thinking of pulling off a 3.29 diff and stick with that ratio but then I started to wonder if I would be happy with that... It was suggested that I go to a 3.42 fdr but I figured I'd try to get everyone's suggestions.

[robertisaar]

a numerically higher FDR is less stressful on the trans itself. i want to say the malibu SS with the 3900s ran a 3.69 final drive from the factory?

[carbon]

Pretty sure all of the GM u-vans(Uplander, Relay, Montana, Terraza) with the 3900 had the 3.69FDR as well.

[fat rabbit]

Thanks robertisaar, the 06-07 Malibu SS did come stock with a 3.69 FDR.

The 06-07 Malibu SS isn't that far off in weight(around a 292.5 pound difference) either compared to a 2010 Impala LT, a 06-07 Malibu SS weighs around 3415.5 pounds and a 06-09 Impala SS weighs around 3708 pounds. Car and Driver claimed a quarter-mile in 15.3 seconds at 91 mph and 0-60 mph in 6.9 seconds, something around those times wouldn't be bad for everyday driving. Fueleconomy.gov states the 06 Malibu SS gets 16 to 17 mpg in the city(the wagon gets less) and 24 mpg on the highway, a 2010 Impala with a 3900 and 3.29 FDR gets 17 mpg(city) and 27 mpg(highway) so switching to a 3.69 FDR would get me around the same city mileage and -3 mpg highway mileage as apposed to going with a 3.29 FDR and I could live with that considering all my driving is city.

Though this is all just random information I pulled out floating around on the internet and who knows how accurate it really is, I can't confirm GM U-vans coming with a 3.69 FDR stock but I could defiantly see them coming with them stock.