Stiffening the kiwi t-frames

When I planted the kiwis I sunk some 6'x6' posts then mounted 2'x4' crossbars on either side at the top to support the vines once they get long enough.  Ever since then I meant to stiffen the crossbar  with other pieces to join the two sides together. 

Today I finished one of the t-frames. One more to go.