I will try. First of all, 4010 sway blocks are drilled and tapped for the securing hardware. 4020 blocks have drilled holes and square “pockets” for square nuts to secure the blacks in position. Next in your pictures, that hex head bolt thru the drawbar support will NOT work with the sway blocks. You will need two R41015 special headed bolts and two 12H292 internal tooth lock washers. Now at serial number 36784, the block part numbers changed, and I have no idea what you may need, but early tractors used R26815 R.H. and R26816 L.H. Later tractors, AR31560 R.H. and AR31561 L.H. These subbed for the early parts. The bolts that hold the blocks to the tractor are regular 1/2”x3” grade 5. Hope this helps.