Early cars use extensions (likely off the shelf male-female threaded standoffs) on the tie rods. That stopped somewhere around S2 production, presumably in the earlier half based on various murky sources. My S1 has extensions on the tie rod.
Later cars used the larger, also hexagonal extension on the steering rack itself as you've shown. Most people seem to believe this improves bump steer so your data here opposes that somewhat. Not sure if Lotus has any notes in their service bulletins or manuals regarding the reasoning for the change.
Page 7 Section H of the workshop manual seems to show the earlier version.
I have sourced the adaptor sleeves, part number 129963 I think, which replace the hexagonal extensions, and I have found a very simple way of extending the tie rods, so I can see whether the earlier S1/S2 steering rack geometry or the later TC/TCS geometry gives more stability when driving down normal country bumpy roads.
The cost of these parts appears to be surprisingly very little, so if it works, then this is an easy and cheap modification. If it does not make any noticeable difference, maybe I would need to do a 3 year university degree course in steering geometry, and a PhD majoring in bump steer to try to understand how it all works.
