Legionario; Yes there are tools for making different LODs in 3ds but since they reduce the number of vertices in the mesh they also interfere with the vertex weights, so you will have to re-weight most of them under the skin modifier.

Both tools are modifiers that are applied to the mesh. The first one is called MultiRes which is probably the easiest. Just turn of vertex merging, set your threshold and hit the 'generate' button at the bottom. The under resolution simply adjust the vert.percent until the desired level is reached.
There are other ways to fine tune it buts that the basic idea.
The other modifier is Optimize. I dont really use this one too much because I find it more cumbersome to figure out the exact parameters needed to achieve desired results.