Sounds like a 5 speed non overdrive..
You may want to get a service manual before you attempt to remove the front pulley.
Many Detroit's (but not always all engines of the same model) have a cone shaped washer that helps to center and lock the pulley to the shaft, if you don't figure this out, and remove the washer first, you will ruin the pulley or hub while attempting to get the pulley off. also don't hook a puller around a dampener, but you probably already knew that...
Grigg
