I am sorry for assuming. Of course I've looked at the data sheet, and I had erroneously assumed that anyone replying would have done so too.
Now, given that everyone in this discussion knows what they're on about, I need a pair of crystals, which will give, when multiplied by 32, 1)a frequency in the range 868-870 MHz, and 2) a frequency separated from this by 10.7 MHz, or another common IF frequency that I can get a filter for. It seems probable that I may be able to obtain a kit, consisting of a suitable pair of crystals, an IF filter, and an 869 MHz SAW filter. If anyone knows where such may be obtained, please let me know. Thanks