Many things are said in this topic. There are some things to keep in mind: Any transmitter/receiver combo you buy will work as long as they are on the same freq.band (in your case 40mhz FM) A 40MHZ FM transmitter and 40mhz AM receiver will not
work! All receivers made 1990 have a BEC system on board, so don't worry about that. I run myself a Sanwa M8 transmitter (40FM) with a Futaba receiver (40FM) in my Yokomo LCG. In my 1/18 XRAY M18 I run the same transmitter but with Jeti receiver (40FM)
and last but not least: in my 1/8scale hydroplane raceboat I run again the same transmitter but with a Multiplex Pico receiver (again 40FM). So you see you can run any transmitter/receiver combo as long as they are on the same freq band.
Hope this will help you.