You can put it in but it will hang over the tailgate and not be flat on the
truck bed.  Or, you can put the tail gate down and it will hang out.  Works
OK for  me.

JEB
2005 Dakota Club Cab

Model / Drive SLT / 4x2, ST / 4x2, Laramie / 4x2

Cargo Area (Bed) [ft3] - Width (Wheelwell to Wheelwell) [in] 45.2

Cargo Area (Bed) [ft3] - Length [in] 78.8

that was coppied off the dodge website.

a sheet of ply is 48" by 96" (4'x8')

I have an '02 Dakota Quad Cab.  The manual says that if you lay 2x4s
into the bed liner slots then it'll haul 4'x8' sheets flat.  I've never
done that, but it comfortably holds 4x8 sheets by leaning them up on
the closed tailgate.  Too much weight would damage the tailgate, of
course.

Not exactly a work truck, but the first day I had mine, it hauled a 4x8
sheet of plywood, a keg of beer, and five people on leather seats.
That, plus it'll beat a Mustang in a drag race and fits in my garage.
Not many other vehicles can do all that.

-rev