The coil pulls the switch contacts open/closed (I think you knew that,) the resistor "absorbs" the back EMF induced when the magnetic field collapses (when the relay switches off) and a diode version does exactly the same (but it must be wired up with reverse polarity, which doesn't really matter unless you're designing your own circuit.) Now that it's confirmed that we're on the right track, these are ISO relays, so any that match the specification will do.
Does yours have a resistor? If I remember from another thread it's for your PTT? If that's the case, the resistor is just to prevent long term damage to the switch contacts, as 200V or so will jump the gap causing premature failure, for a spare, I wouldn't even bother about the resistor.
TYCO Relay VF4,40/60A --- Pennine Components
Has them even cheaper, 10 minutes in a scrapyard might get you them free!