I have a 03 Screw 4x4 with the 5.4. It currently has an open diff with 3.55 gears. I want to upgrade the diff with a limited slip and also put in some 3.73 gears. Where is the best place to get the front and rear gears from?

Thanks,

 

Changing .25 or so in ratio will yield very little change. A .50 or more change in ratio becomes more effective. That being said, with ratios like 3.73 that Ford offer, their gear sets are easy to set-up and are quiet. When going aftermarket, I've found these to be high quality and quiet:
www.usgear.com/tl_truck.htm

 

i like www.4wheelparts.com i have spent over 10,000$ on my jeep and truck there in parts and they are great, good custumer service too