Hi everyone, I found these links that can help for Mexican bus identifications.
https://www.facebook.com/autobusesurbanosmx
https://www.facebook.com/TransporteTulancingo

For this one, the advantage is that a referencing is done by Constructor or Bodybuilder in the left column.
https://autobusesurbanosmx.blogspot.com/

I have already commented on some of the changes.
http://www.imcdb.org/vehicle_376555-Havre.html
http://www.imcdb.org/vehicle_229351-Havre.html
http://www.imcdb.org/vehicle_251198-Havre.html
http://www.imcdb.org/vehicle_1241979-Havre.html
http://www.imcdb.org/vehicle_1175331.html
http://www.imcdb.org/vehicle_406829-Havre-II.html
http://www.imcdb.org/vehicle_165242-Havre-II-1990.html
http://www.imcdb.org/vehicle_504484.html
http://www.imcdb.org/vehicle_1176180.html
http://www.imcdb.org/vehicle_97982-Havre-Micro.html
http://www.imcdb.org/vehicle_415454.html
http://www.imcdb.org/vehicle_774812.html
http://www.imcdb.org/vehicle_758929.html
http://www.imcdb.org/vehicle_1222024.html
http://www.imcdb.org/vehicle_1224212.html
http://www.imcdb.org/vehicle_1393687.html
http://www.imcdb.org/vehicle_1342018.html
http://www.imcdb.org/vehicle_1342169.html
http://www.imcdb.org/vehicle_1468910.html
http://www.imcdb.org/vehicle_1253398.html
http://www.imcdb.org/vehicle_1268918.html
http://www.imcdb.org/vehicle_391399.html
http://www.imcdb.org/vehicle_1474331-Havre-Micro.html


For those:
http://www.imcdb.org/vehicle_415455.html
http://www.imcdb.org/vehicle_415457.html
http://www.imcdb.org/vehicle_504491.html
http://www.imcdb.org/vehicle_1343232.html
http://www.imcdb.org/vehicle_1343239.html
http://www.imcdb.org/vehicle_1268926.html
http://www.imcdb.org/vehicle_675138-Havre-Micro.html
http://www.imcdb.org/vehicle_166047-Havre-Micro.html
http://www.imcdb.org/vehicle_97981-Havre-Micro.html
http://www.imcdb.org/vehicle_414722.html
http://www.imcdb.org/vehicle_1258951-Havre.html
http://www.imcdb.org/vehicle_1176191.html

I am taken as reference this one.
http://www.imcdb.org/vehicle_867191-Alfa-30-30-Microbus.html

But the brand does not seem to be "Alfa 30-30" but only "Alfa".
https://autobusesurbanosmx.blogspot.com/search/label/Alfa

"30-30" seems to be the model, but I’m not sure.
https://fr-fr.facebook.com/autobusesurbanosmx/posts/1232399650250858/
https://hi-in.facebook.com/295234097745621/posts/chevrolet-alfa-30-30-ruta-56buen-fin-de-semanaempezamos-con-todo-/321262581809439/
https://www.flickr.com/photos/metroferreo/29616470140/
https://www.youtube.com/watch?app=desktop&v=KJX983TpDyI

Besides, "Havre" is not a manufacturer.
http://www.imcdb.org/vehicles_make-Havre.html
According to this link, "Havre" seems to be a model of the manufacturer "Eurocar".
https://www.facebook.com/page/663222493697407/search/?q=Havre

But in it’s links, the term "Havre" seems to be a nickname
https://www.facebook.com/page/376068162550682/search/?q=Havre
https://autobusesurbanosmx.blogspot.com/search?q=havre

The term "Havrecito" is even sometimes used.
https://www.facebook.com/autobusesurbanosmx/posts/1834018180088999/
https://www.facebook.com/autobusesurbanosmx/posts/1846020198888797/
https://m.facebook.com/autobusesurbanosmx/photos/a.376074789216686/1628098267347- 659/?type=3&source=57&__tn__=EH-R