03:32 Jan 17 

Diablo es una palabra muy común en México para referirse a ese sencillo medio de transporte de cargas relativamente pequeñas, como los sacos de harina de maíz.

02:12 Jan 17 

That might be a little far-fetched, but of course we don't have the rest of the story...

01:37 Jan 17 

It could actually be an the devil, or a spirit or a soul, or the evil part in the ambitious sense of uncle Mario. If its implying a food shortage, it seems to me that it is saying:

I ask uncle Mario to accompany them with his devil/spirit to bring the bags of Maseca.

It would seem as if they need the help of uncle Mario's devil to make sure they bring in the Maseca. I don't think its referring to any kind of vehicle... I could be wrong here, but that's what I understand from the short context you have provided... Goog Luck!