What are the symptoms of a bad diff?

I have been having trouble with my 88 4runner. It has a 3vz-e engine efi 3.0 v6 with an auto transmission. I just changed out the fuel filter and made sure that my vaccum hoses where in good shape so I don't think the fuel system is to blame. The engine gets plenty of power and fuel but the truck jerks back and fourth when I am accelarating especially up hills on the highway. It is intermittent. I know that my rear diff is on its way out but I am not sure if that is the problem. I guess it could also be my auto trans. What are the symptoms of a bad trans or rear diff? My trans seems to shift okay. maybe a little rough but not too bad. There is plenty of fluid. Sometime my overdrive doesn't kick in when I push the button but for the most part it does work. The rear diff makes a small klunking noise when I decellerate and that has been on going for a while. Any ideas on what the problem might be? Please help me save my beast.... Thanks

If you haven't recently, grease the fittings in the rear propellor shaft.

It might be a cylinder misfire, I had a problem very similar to yours, and thought it was my auto tranny, but it turned out something had "eaten" through my spark plug wire.

If you haven't recently, grease the fittings in the rear propellor shaft.
HI Brian R. Thanks for the help. I will try and have the shaft lubed. I noticed that the problem only occurs when I am accelarating. It doesn't happen when I push the gas with the engine in park. It also doesn't happen when I am rolling along with my foot off the gas. That is why I am thinking it may be an auto trans problem. Does this info give you anymore ideas?