I've read some old posts about needing an adapter to hook up an after market tach, but all that requires running wires to the engine bay. Since you can swap clusters in with a tach, obviously there is a wire leading out of the gauge cluster that tranmits the RPMs. Would it be possible to connect my tach to that ? Or would I need to go ahead and get the adapter and run to the coil pack?

buy the adapter, i tried what you want to do(the cheap way). unless you have a tach that can run on a one pulse system it won't work.

you got a 2.2 you need an adaptor. dont buy the rk one, its junk. get the autometer one. i hooked my tach up in about 5 mins. hardest part was actually mouting the tach. on the coil pack there are 2 harness's. a 6 pin and a 2 pin. you want the 2 pin. you'll see 2 wires coming off the harness. the wire you wanna cut and run into in the pink wire (or it might be purple). check my cardomain page. i have pics posted on there on what to tap into and shots of the engine bay so you can find it