Congratulations on this spectacular kit!
If I understand you correctly you wonder if there were running changes in the production line of the XLS. At the time I had all the first three versions of the CAT one after the other (400, 401 and the 403). Now I’m building the 402 (2 WD XL) posted here:
https://www.rc10talk.com/viewtopic.php?t=50034
There were several changes to the production line to both the T400 and T401, of which some are described in the above thread. However, the T403 seemed to have very few changes along the production until the release of the Procat.
The XLS was released early spring ’88 and I bought my kit as soon as it was available, well before the summer race season. One thing that I remember from my kit was that it came with the "blank" 3 mm turnbuckles for all ballcups as per manual. I’m also nearly positive that people I knew buying the XLS in ’89, had hexes on both steering rods and rear track rods turnbuckles. Other changes than that I have never noticed. Would have been interesting to see if there were other changes on the later runs of the XLS prior to Procat.
Other comments:
The grey bumper depicted on the box never came with the XLS. The wide black bumper was available autumn '87.
The wide centre trackrod (T170) came with the XLS, but was not on the World Championship XL CAT. The rereleased XLS Masami is in this respect truer to the car used at the worlds sporting the old and narrower T116.
Same goes for the wide rear suspension bracket (T154) included in the original XLS kit, but not on the car driven at Romsey. The angle of the rear suspension bracket was steeper on the XL worlds car.
On the other hand, shock internals, screws and hole pattern in the chassis are again different on the rereleased XLS Masami.