Problems with an RF receiver from an old car alarm

First -> i know that a rf receiver module is very cheap but where i live the shipping is x3 then the module

Because of that i just unsolder an old rf receiver from an old car alarm who look pretty much like the classic 433Mhz module but when i'm trying to receive something from it's Transmitter i got nothing then this:

What i just discovered writeing this post is that on the transmitter it's said 420 so maybe this is the frecvency ?