You must simply be ordering the incorrect version.
There are 12 different 727-200Adv that you can order, ranging in ranges from 2110NM to 2610NM. The only way to get 2610NM is to get it with JT8D-17Rs in a +11.2tn MTOW variant.
I've been known to forget to click the right variant when I order or forget to pick the configuration. It happens.
If you just got the 727s, check your Aircraft on Order page, they should still be displayed for a short while after you take receipt of the planes. It will show the engine and weight variant choice you made at order.