The LNBF for 105 will work for FTA. That is, as long as your receiver will accept it. It is probably a DP or a DP Plus LNBF and it may require more power to operate. Also, the FTA receiver may need a special entry selection for a DP or DP Plus device (OS2 or something like that). Not many FTA receivers provide this option and many that do, do so because a third party software has been compiled to supply this option, which means a "Jolly Roger" firmware.
Your best direction would be to use standard linear or universal linear LNBFs for your FTA purposes. Sell the DN LNBFs on E-Bay and use the proceeds to purchase more appropriate devices. Those which will match most all FTA receivers. I should say that this is just my own personal opinion.
RADAR