I'd put with post G1 (assuming that where things like Tigertrack go) as Hauler didn't appear in the constructicon green he appears in since.
I would personally have him with wherever I put my Diaclones or variations like Clampdown. For me, that means as a back-up squad in the G1 collection.
But if there is a distinct Post-G1 mark in your collection, then it should go there.
In my mind, either everything G1 related is in part of the extended G1 or nothing is.