The rear support under the boat is called the strut... Inside the strut is a brass tube with a rubber lining called a cutlass bearing. It is water lubricated - no oil, etc... If its squealing - stop using boat NOW or you'll likely cut grooves into your shaft. You'll need to replace the cutlass bearing.
The through hull fitting from the engine compartment (through the hull) into the water is called the shaft log. If its squealing - stop using boat NOW or you'll likely cut grooves into your shaft. Your shaft log may be too tight - you may want to loosen it a bit, get a good drip of water coming in and then try the motor in forward/reverse.
Either way, it sounds as if your cutlass bearing &/or your shaft log may need replacement. Ron or Dan Tanis (both on here) can help you with parts & procedure.
