Upper A arm identification and placement

I have a 66 Jaguar S Type that I purchased for restoration. Many of the parts had been disassembled prior to me getting the car. I am in the process of refitting the front suspension and would like to know if the upper A arms are interchangeable. They are not marked left or right.

There is a left and a right one.
The upside is where the Bumpstop is mounted, the threads should be on top.

Here my S-type front suspension ( converted to rack&pignon )

There are four upper a arms. Two on each side as you have pictured. They all have stamping marks on them. Two different stamping marks but no part number differentiating left from right. I know how they attach, i just don’t know if it matters which side they go on.

Thanks for your help.

Interesting photo. What brand/type of rack are you showing? It looks narrower than mine which is a ZF type used on a late XJS. Here’s mine from below. I wonder if a narrower rack makes any difference in preserving the Ackermann effect but it does not look like the pinion could be moved any closer to the center of the car due to closeness of the sump.

It has a XJ6 S2 steering rack, it was on there when I bought the car.

Here you see it’s location better.
The steering tower bottom is almost hitting the sump.

I have all the hydraulics removed, and installed electric power steering.
Here you see the location under the dash ( MK1 )