I purchased this kit from a Chinese seller on Ebay. The kit was so inexpensive that I decided to take a chance on it to use with my Yaesu FT-817ND. Overall the kit works as advertised but lack of documentation on hoe to actually put it together is a problem. If you are familiar with amplifier circuits you should be able to get this together and working.
The link to the sellers Ebay listing:
http://www.ebay.com/itm/DIY-kits-70W-SSB-linear-HF-Power-Amplifier-For-YAESU-FT-817-KX3/182254657820?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D39344%26meid%3Dea34919aad7f4f28b24f27719138f586%26pid%3D100009%26rk%3D2%26rkt%3D2%26sd%3D152093756341