I dropped my digital Futaba servo right in my truck with no changes to the radio system. I have since used a Air Blazer sport (am) radio and a Futaba t3PDF (fm) radio, both worked fine.

They do definitely drain your receiver batts faster. I was running two digitals on my truck, one on TH/Brake, one on steering and I was only getting about 5 tanks before a fully charged pack would dump on me.

I have since switched to a analog servo for TH/Brake and I get about 8-9 tanks before needing a recharge now. BIG difference