Hi Eamonn,
Ah, okay now we know what you're trying to do.
As it turns out, there's actually a guide here on iFixit for removing the battery cells in your drill!
[guide|61996|DeWalt DC970 Battery Cells Replacement - iFixit Repair Guide|new_window=true]
That'll get you most of the way there. I was faced with a similar dilemma; I had an older drill that was no longer made, and battery packs couldn't be bought for love nor money. I figured out how to open up the battery pack and it turned out the most cost-effective way to replace them was to buy the packs being sold by Harbor Freight, disassemble them and rebuild my own battery pack using the cells scavenged from the HF packs. Unfortunately, it doesn't look like those packs are being sold any longer.
Anyway, you're looking for SubC size batteries, and you want the mAh rating to be at least as high as the existing ones, or you'll reduce the runtime available on the pack. You can always go higher; if your drill is older you may be able to about double the mAh rating of your battery pack. Here's a set on Amazon that should work; you just have to arrange the batteries in the same position and polarity as the existing ones, solder them together in that configuration and pop 'em back in and Bob's Yer Uncle; there you go!
[link|https://www.amazon.com/Tenergy-2200mAh-Wrapped-Rechargeable-Batteries/dp/B002RY9OO0|Amazon.com: Tenergy NiCd SubC 2200mAh Paper Wrapped Rechargeable Battery Flat Top with Tabs - 15 Pack : Automotive|new_window=true]