ORIGINAL: KINGX
Futaba and HiTec systems are "negative shift" and are compatible with each other either way. Jr and Airtronics are "positive shift".
Yes, you can use Hitec receivers with your 6EXA.
Just to clarify, not ALL HiTec receivers are Futaba compatible. Many (most?) of their receivers are available with either Futaba or JR/Airtronics shift. If buying, be sure to get the correct version, or choose one that is shift selectable.