this is the 3 piece. the frame in the back is the optional piece they offer.
if you do not get the 3rd piece you will need to make some adjustments to your stock frame. looks better with the 3 piece but thats just me.
this is the stock frame i removed. you can easily see the difference in them. the 3rd piece AM offers has the holes ready to fit the pony perfect in place. and with the stock fram you will need to cut out some holes to make the pony fit in place