Hi CBP3D,

you can throw on a keyframe for your extrude, however afterwards you can't delete history on that object, because then you will also delete the keys, because the extrude history get's deleted...

I have attached an animation test file, in the thread Alan is talking about here... -->Extruding Faces over time or you should be able to download it by clicking here...

I will see if I can find the Maya file for it...

regards

Strarup