Was it in there before you took it out, or did it come disassembeled?
I've done it twice. Both times, the bottom of the dash was damaged from the cab and steering column vibrating out of sync, (stress cracks and broken metal) so I removed the brace for weld repairs.
Took a little time with a totally empty dash to work it into place, but they went in. Get the brace completely up behind the dash before sliding the studs in, then drop the end down on the bottom of the dash.
Are you sure you're using the correct holes in the firewall for the stud end?
