If you want to some (bullet proof diffs) get these.. I have them and they are great!!, i been running run them on my GR3 E-Revo on 6-8s for the past 8 months and have had no problems at all with them..
Just a thought..
http://www.rc-monster.com/proddetail...rod=rcmflmrvdf
P.S.
Yes I know you mentioned the 3905 and these are Revo diffs, but hey that’s why there is fabrication..