Is an external oscillator for MAX2769 GPS receiver needed?
Maxims 2769 does not include a crystal. It does include an oscillator that is able to excite an external crystal. Load capacitance for an external crystal can be tuned with configuration registers to slightly pull it to counteract aging.

An active external oscillator can also be used, but pulling is not supported in this setup.

The wording in the datasheet is somewhat sloppy about this. If the unit would include a crystal, you can be sure MAXIM would advertise the fact more clearly and also give performance characteristics for it.

Choose a (low-end) TCXO for GPS, a cheap uC crystal will boost phase noise (might work, but will degrade link budget).