A well-established fact about the grammar of the Germanic dialect Mòcheno is that the observed syntactic variation in the position of the finite (V2 and V3 word orders) and non-finite (OV and VO word orders) verb forms should be understood as intraspeaker variation fed by system-internal constraints at the syntactic-semantic interface. This paper documents a case in which system- external factors do play a role in an area of Mòcheno grammar. More specifically, it will be shown that V3 word orders in sentences involving a weak subject pronoun are subject to diatopic and diastratic variation. Diastratic variation is only found in the variety spoken in Palù and involves the age of informants: V3 is accepted by elderly and young speakers and rejected by middle-aged informants. This type of variation, far from being an unexpected development, will be shown to be a conservative trait of Mòcheno grammar.