Not only does Futaba NOT recommend base loaded antennas... the last time I checked they will not tune & align one to your receiver even if you are willing to pay for them to do it. My guess is they won't do the conversion nor recommend it because Father / Mother Futaba says nope!

The loaded antenna's really have little advantage over a full whip or creative routing of the original wire antenna, other than being an easy way to get the antenna out of the fuse. The fact is if you do a good range check after installation.... use the type that works best! Generally the loaded type antenna will work fine if it is tuned & aligned properly to your receiver. Routing the wire antenna out the leading edge of the wing is a great way to conceal the wire while at the same time getting it out of the fuse area quickly.
Lee H. DeMary
AMA 36099