For the Dnepr there would not be the "A" arms. In stead the front lower mount would be cut off of the sidecar frame and a pinch tube type clamp welded in its place. A new lower rear pinch tube type clamp would be welded about 8 inches forward of the current location for the lower rear mount. Then we would slide in a part we call a clamp. This also has pinch tubes on the end of it set at 70 degree's. Then into the clamp a part we call a boss slides in. The end of the boss has threads for the 5/8 inch heim joints that attach to the clevis on the lower mounts on the bike.
We provide drawings as to how to cut off the front lower mount and weld in the new pinch tube type clamps.
BTW, the Ural is very similar to the Dnepr however the frame tubes are different diameters.
The "A" arms are what we use on our M72 type sidecars on the V stroms and the R1100 and up BMW GS bikes. We would also use "A" arms if we were doing a Ural or Dnepr in house.