You need to first tell us whether you are removing an auto or manual box. You need to have a jack under the oil pan on either type to support the weight of the engine. Plus you can crush distributor cap if not supported under the pan. If it is an automatic did you remove the 4 bolts connecting the flexplate to the torque converter? If not this makes it more difficult and could damage input shaft or pump drive if you manage to get it apart without removing converter bolts. There are also two dowel pins on either side of block which locate bellhousing to engine that are a pretty tight fit. I have run into some stubborns ones and have had to pry them apart. Beating on it won't help.It has to come STRAIGHT back until it clears the dowel pins, prying on both sides at once helps. If it is a manual, it could the input shaft binding in the pilot bearing. Again you need to support engine, that way transmission is not "hanging" on the engine. Hope this helps.later,rcs