Thanks all... I'm actually trying to get the kick drum and the snare parts from the original overheads. I've tried with the settings in the Drum Replacer in Sonar and haven't gotten the results I was looking for. I was intrigued by Addictive Trigger.. but for some reason it didnt work in my project..  I was going to try Slate's.. but I read on the webpage somewhere that it really only could handle individually tracked drum parts (or thought I had read that)... 
 
I'll go back to Drum Replacer and mess with it some more. I've tried using the Pro Channel EQ to HP/LP various frequencies to try to eliminate the other drum sounds to let me hit the right setting for the drums but no luck just yet.. 
 
I'll keep at it.

Any of these extraction apps work best when there is strong transients in the recording. But if a drum track has a lot of sustained content, like Hats and Ride, your more or less hooped. 
I've had best results with Drum replacer when its a full multi track recording. 
I too have some old 4 and 8 tracks and they didn't work most likely because the track (s) where saturated and when views the waveform lacked strong peaks. Drum replacers use those peaks/ transients to do their thing. 

TemplesGateStudio
I have an old 4 track demo with some drums on it that I was hoping to "drum replace" and have been hitting my head against the wall.

 
Interesting. But drum samples probably sound better.

TemplesGateStudio
So the drum track I want to rescue is essentially an overhead.. and I've been trying to extract the kick/snare from it to import into some modern "remakes" of the material.

 
From personal experience even isolated microphones can mistrigger DrumReplacer, requiring the occasional manual fix. Other drum replacers rely on algorithms, which sometimes fit, sometimes not. And not all drum replacers can output their result to MIDI.
 
Rebuilding it as suggested by chuckebaby is the way to go. If it's straight rock, it won't take long.

TemplesGateStudio
Thanks all... I'm actually trying to get the kick drum and the snare parts from the original overheads. I've tried with the settings in the Drum Replacer in Sonar and haven't gotten the results I was looking for. I was intrigued by Addictive Trigger.. but for some reason it didnt work in my project..  I was going to try Slate's.. but I read on the webpage somewhere that it really only could handle individually tracked drum parts (or thought I had read that)... 
 
I'll go back to Drum Replacer and mess with it some more. I've tried using the Pro Channel EQ to HP/LP various frequencies to try to eliminate the other drum sounds to let me hit the right setting for the drums but no luck just yet.. 
 
I'll keep at it.

I'm surprised AT didn't work on this. Did you adjust the threshold, the sensitivity and use the fingerprint for the kick hits? As much as I love Slate Digital Trigger, AT is amazing in this situation.
 
Rocky

Sound Radix Drum leveler has an excellent expander. You'd probably have to copy the overhead and use two instances, one for the kick and one for the snare. It has a side-chain filter that includes or excludes certain frequencies. It's amazing! Hope that helps.
 

Make copies of the drum track and use EQ to isolate each drum sound. Use the drum replacer on those.