The Excel (XL020) is a rebranded Rino Crono. Excel were not coy about this, marketing the derailleur as part of 'Excel's Gruppo Rino', that is 'engineered in Italy'.
The Excel (XL020) uses an excellent slant-parallelogram layout ('borrowed' by Rino from SunTour) and is formed and finished to a respectable standard. Notably, it is fully demountable. There is a decent case to be made that these (and their Rino and Saavedra siblings) are among the best non-Japanese derailleurs available at the time.
The Excel marketing materials describe this derailleur as having Delrin pulley wheels with sealed bearings. Strangely I have never seen an example with these pulley wheels. I have, however, seen several instances of each of two other variations:
Perhaps the the Delrin/sealed bearing units were problematic - either in terms of supply or performance - and Excel fitted one of these options as a substitute.
I am a little confused about the option with the Bullseyes. At the time Bullseye pulley wheels were super-high-end. I might even guess that the retail price of a pair was higher than that of a whole Rino Crono derailleur. Could it be that both Excel and Bullseye were conspicuously 'American' and maybe it was felt to be a wonderful marriage made in some kind of proto-MAGA heaven ("Let's make America great again" was, after all, a slogan used by Ronald Reagan in his 1980 presidential campaign)? Or am I being too cynical? Excel's marketing was heavily based around Lon Haldeman's amazing performances in the Great American Bike Race. Perhaps over 3,000 miles of Lon's aggressive riding was more than enough to shred any kind of plastic pulley wheel. Perhaps the deluxe Bullseyes were genuinely required. It reminds me somewhat of the Gevenalle BURD CX - an inexpensive cyclo-cross derailleur that is available with high end pulley wheels that can resist all that mud that cyclo-crossers do so love.
This fine example of an Excel (XL020) has those red, Bullseye, sealed bearing pulley wheels.
It is set up with only one of Bullseye's spacing washers each side of the pulley wheel. I think this is for, what at the time would be, a very narrow chain. Weight-weenies will also note that the super-prestigious pulley wheels add 8g to the weight of my other example.