You may not have any, but if there are, they will be on the raw water side. Just follow the cooling system from the raw water pump and back to the exhaust discharge and look for something that looks like a brass plug (it may be painted over). It will be located in either the FW cooler, LO cooler or your transmission cooler. Once you find one, unscrew it and it may and may not have a threaded center for a pencil zinc. If it's just a brass plug without a threaded center, you can replace it with the same size plug with a pencil zinc. Just make sure to measure the depth and cut the zinc off with a hack saw if needed to prevent it from bottoming out.
You will not find any zinc anodes in the engine block since they are intended to protect the raw water side of the system where corrosion will take place.