Just to add the last state of my truck to this thread...
I updated my web page with some pictures from 2008...
(the new SAVAGE web page !!!)
An important detail to improve was the (well known) choice of pinion / spur gear, so finally the steal spur gear was replaced by a plastic one (Kyosho center diff from Mike), the problem was that the new diff was longer than the old one, which caused a lot of mechanical works, luckily the drive shafts had enough play. Furthermore a new outfit with new shell, new wheels (these ones really without ballooning), FLM shock towers to lower the truck. A puffed 3s 8Ah maxamps pack was replaced by Mike (he is the best!)...I checked the Quark programming and put now "normal lipo" to avoid high current peaks which are probably damaging the maxamps...(but I'm still sure the puffed pack had a problem with a single cell)...be careful with maxamps..
So now...after some runs the "new" truck is reliable and incredible amazing... can't be better !!!