Just an update. The Savage has been fantastic. The center diff is solid and it makes the truck fun to drive. I still have cogging issues and I just added a smaller pinion to see if it helps.
Latest upgrades:
1. Aluminum shock caps
2. Softer springs
3. One piece aluminum rear hubs
4. 19mm conversion for Losi wheels.
5. Losi Muggy wheels.
I have decided (with Mike's suggestions) to replace the Losi center diff set-up with an RCM Universal diff mount. I will have to fab a plate to hold it. I built a center diff out a HB D8T. My Muggy is getting lonely and wants it's diff back.