take your old balancer with you to compare!
make sure things like the keyway are the same size/depth, the bolt holes line up and that the physical size is the same. Although I don't know if one is even made, it is possible to have a larger/smaller balancer with the same imbalance. This might complecate the instalation of your pulleys etc. later. And finally you'll definately want to check the center bore diameter. When comparing it would be great if you had a vernier caliper (measure's very accurately) but not all that necessary cause if they look the same and are approximately the same bore then it will probably fit on the cranshaft.
Getting the balancer off is always a job and a half. but don't be afaid to realy beat on that piece cause you're gett'n a new one any ways.
One suggestion for reinstalling the new balancer that makes life a lot easier is to set the balancer in a sink and let hot water run over it for a while mabey 5-10 min. or so. be carful when you pic it up you might need gloves, it'll be HOT
After that it should just about slide on. Now use a rubber malot or rubber ended hammer and whack that balancer on as hard as you can... before it cools.
PS. make sure the keyway is lined up and has the key in it!
Also I know it is a lot harder to remove tha balancer with the motor in the car sooooo have fun.