I had a look through my stash of old UART/timing crystals and found some old/decent/unused IQD crystals that still have a known spec with them.
These are 4.032MHz crystals and they would have been intended for use with a modem IC some time around 1996. There's no date on the bag but I remember that these were intended for use in a little low power module that had to survive being buried in frozen ground or in hot sand and could be deployed anywhere around the world.
The temp spec is over -40deg to +85degC and the initial cal tolerance is 15ppm and the load capacitance is 30pF. I'll stick one on the VNA later tonight and maybe also knock up a test osc circuit and compare all of them for how much variation there is in frequency between each crystal. I've still got 8 of them in the bag and they are about 20 years old and these have never been used
