I don't know for sure, but from all the photos I've seen the 1x12 ext cab is the same size as the 1x12 combo... and that doc shows the combo size.

then from the photos the head looks to be about the same width and depth as the ext cab, and around half the height of the cab.

Hope this helps

Rowbi

So the head is 25" wide and the 1x12 Combo is 21" wide.

That seems odd that the head is wider than the combo and extension cab.