Just about to start the build on the sc10 4x4. I have heard people saying that there diffs in the kit sometimes doesnt come pre-assembled with enough diff fluid in it? If that is the case, is it better to just open the diff up and check? And if the diff doesnt have enough diff fluid in it, should I use more of the stock weight for the diffs, or are people changing to a heavery/lighter diff fluid? Any help would be appreciated