On eBay there are still quite a few of the "CONEXANT NAVMAN ROCKWELL JUPITER GPS TU30 D140" receivers available at a good price, individually or in 5 packs. This is the model that we have been using for VCTXO locking and etc. Look at eBay items numbers 320086778609 (5 pack) and 320086778737 (single receiver). 73, Jerry W7QX