1996 Saturn SL2 Where to drain?

Your drain is on the top of the transmission which is really under the car since the transmission is mounted in upside down. You can't miss it if it's the factory one and no one changed it. It will be gold with a 15mm head you just take it out and drain the transmission. The filter is just under the airfilter box for your engine if you remove the box you will get easy acess to the filter it just screw's on like a oil filter. It's very unlikely that changing the fluid will cure your Knocking while driving. So when it shift's does it shift really hard?Causing this knocking noise?Does the transmission slip while drive?Go to a auto part's store like auto zone and have them scan the code's if you have any code's let me know what the number's are.