Inrad makes a kit for the FT-101 series, including the FT-101E, for adding 12m, 17m, and 30m. The cost is all of $45 including the new rocks. I did one years ago and found the installation mechanically challenging (wiring to the various wafers of the bandswitch in particular) but it went well and worked well.
See:
http://www.qth.com/inrad/kits.htm#yaesu73,
Caity
K7VO/8