[19Fordy]

Here are photos of the after market tube shock kit that was installed on my 40 in 1963.
The special shoulder bolts supplied with the kit are longer than stock and go through the radius arms and backing plate. They replace the stock backing plate bolts. The socket that fits the bolts is 1 inch. So.......... perhaps this is what you have on your car. Photos 3 and 4 need to be rotated in your mind 90 degrees. both bolts are 1 inch.

Time for you to post some photos, if possible.