Check the regulator and channels at the same time, since a worn mechanism is what cracks new glass.
Door glass fails at the mounting points when the regulator or channel is worn, so a new pane fitted to a worn mechanism tends to crack again within a season. Check the channel felt and the regulator roller before fitting. Solar-tinted, privacy-tinted and plain glass are different part numbers, and a pane with a factory vent or quarter-light cut-out will not interchange with a plain one.
