For 37s, you will want to go with 4.30s without a doubt.
If you were to tow really heavy 12k+ I'd say 4.56s, but they will also net you worse mpg unloaded on the highway.
As for gears, call up Reider Racing.
Not sure what all is available aftermarket for 4.30s....you may have to go OEM.
If you go aftermarket, Precision Gear is the only brand I would run.....that is what I run.