Black Fender Stratocaster
Kurt had several of these imported cheaper Stratocasters that he would smash at the end of the set. These were Japanese imported Fender Stratocasters.
Based on the wear patterns of the broken body it matches that of the photograph above from 1991. The body shown above is (as of December 2008) on display at The Grammy Museum in Los Angeles, CA.
Here is a video clip of Kurt splitting the body in two and distributing it to the audience. I have no idea how the two pieces were able to reunite after such a journey! (body splitting at 2:39) (update: video removed by YouTube copyright police. Trying to locate another)
Update: This body is currently on display at the EMP's Nirvana exhibit. According to a video on mtv.com with Jacob McMurray, this Stratocaster was smashed during the recording of Endless, Nameless for Nevermind. Here is a photo of the black Stratocaster smashed during that session. Note: body is not split in two.