Bicycle Mechanics - Explain SRAM compatibility to me...

I've got an 8-speed SRAM shifter that I was given by someone who had just done a singlespeed conversion on his MTB. The problem is, I don't have the rear mech the shifter was operating, as it was bent (which is what prompted the singlespeed conversion). What I want to know is which SRAM rear mechs will be compatible with it. Is the cable pull different for SRAM road and MTB rear mechs? What about a mech designed for 8-speed, will that be different to one designed for 7, 9 or 10? To make matters worse, I've seen "Shimano-compatible" SRAM shifters as well, how do I tell if the shifter I have is one of those? It's in my shed somewhere at the moment, but I can go and find it if pictures, or the model number, would help.

Thanks in advance

What SRAM shifter do you have? That would help for sure. Some grip shifts are Shimano compatible and they would work wiht both Road and MTB rear mechs from Shimano as well as some SRAM rear mechs as all of these are 2:1 ratio. Example - Attack Grip shifts http://www.sram.com/sram/mountain/products/sram-attack-twist-shifter

All SRAM X series grip shift are 1:1 ratio and will only work with SRAM 1:1 rear mechs ie. X.7 - X.9 etc.
http://www.sram.com/sram/mountain/technologies/311

It's a thumb shifter, a sort of "rapidfire" one. I think it's an X-series, maybe X.7, I can't remember. I'll know more tomorrow, hopefully, when I find it among all the junk in my shed.

If it has a name (like Attack) it is for Shimano, if it has a number, it is for SRAM mechs.

or if it has 'TRX' on it its for Shimano

Thanks, it's definitely a number. I'll start looking for a rear mech.