I think they chose not to use the Carrera name on this one for the case shape is the same as the 510.50x and not the cushion one of the L5100 Carreras (510.511 and 510.523).
On the other hand this is really a wonderful piece and I remember Chuck writing it was probably one of the very few Lemania 5100's ever put in gold cases: I only know of Fortis Cosmonauts as well in fact. How heavy however this should have been: already the steel-cased ones are some of the heaviest watch I've felt.

As for a contest between the Pasadena and the 510.501, I may certainly be biased towards the L5100 but it's really no competition in my opinion: it's the 510.501 a thousand times over - fluted pushers, much brighter dial and of course a L5100 at its heart. And I do own a Pasadena as well, and I like it...

Cheers.

Fabrizio