There is very little info out there as to what pre-Evis examples actually were. The best I could find was the above example from Ed, with a lot of interpolation on what I know of early Evis details and construction, paired with looking at as many examples of Rodeo Uncle jeans as I could. The early designs are incredibly fluid. Same model number 5501, but everything from denim, hardware, construction details change.
Early Evis (that I have several examples of from the first runs where they did partial runs of stitched arcs prior to full adoption of painted gulls) all have red line denim with a wide selvedge, scovil hardware, diagonal mounted rear belt loop, left side installed care tag, with very odd stitching details like overlapped stitching (almost like they ran out of thread and restarted) with a very dark orange/almost brown thread. The details of fabric, thread and minor construction changed very rapidly even while still "Evis". Selvedge got narrower, thread became a more standard yellow and orange, odd sewing behaviors disappeared, but scovil hardware continued until a later era (present in post-Bull patch Evis).
My above pair of Rodeo Uncle have the exact same details of construction, thread and hardware, look like a pair of early Evis, save for the denim. It is a pink line denim with a narrow selvedge.
From all of the other Rodeo Uncle examples I have seen, denim changed first (somewhere there was my pink line and a red line) along with a transition to using YKK rivets alongside Scovil hardware (mine are all scovil), construction details diverged away from Evis-like details (offset beltloop, different thread and sewing techniques, pocket shape and placement), then a change of hardware to "Standard Style" shop branded hardware, along with patch changes (that I am less clear on).
Based on this information, I think it is logical to suggest that those examples which have scovil hardware and Evis-like construction where made from the "shop" that became Evis, and the transition away from Evis "fingerprints" likely signals the pre/post boundary. Now, I do not know if between mine and Ed's, which is earlier. Its clear to me that the thread used on Ed's pair is the identical brownish thread in mine and early Evis. You can interpret the all scovil hardware vs the some YKK as being an indicator of Ed's being a transition pair (because Evis is all scovil and YKK as the company name didnt come about until '94? I think, so after this era which was ~'88-'90).
The ONLY detail that seems to be a clear indicator that I have been able to pick up on, which I even hesitate to say, is the stamp font used on the patch.
Every example I have seen BUT my pair, including modern examples, use a "curly-er" font. See Ed's below and another example below:
Eds:
Whereas my pair has a very plain font:
I have not seen this font used on any other pair, (nor a deer skin patch). This might be the best determining detail.
Thanks for giving me the opportunity to nerd out @julian-wolf. I hope that answered your question.