Most other major car audio head unit manufacturers size to fit the Toyota dash. You can see a clear size difference in Marks installation here -> http://mse.ufl.edu/~mark/empeg/pages/P1010019.htm
However, empeg is not to blame for this. To make a pull out unit fit in this space, the unit would have to be about 1/2 inch smaller side-to-side.

Alex Lear