I replaced my IMS bearing with an upgraded fully sealed high temp steel ball bearing.
This is not terribly difficult to do, but there are a series of steps that must be carefully followed or you'll upset the valve timing and have a very bad day. The cause of this is the valve springs are capable of rotating the cams if the engine is not set at TDC. At TDC the lifters are all located on the cam circles and not on the cam lobes so the valve springs cannot rotate the cams.
When changing the IMS bearing, one must loosen the timing chains. It is at this point if the valve springs are pushing the lifters against the lobes of the cams instead of the cam circles, the timing chain can slip over the cam sprocket and valve timing is lost. It made a loud scary noise on the engine stand, then I made loud scary noises.
Lots of very experienced folks (for whom I have a great deal of respect) disagree with going back with a sealed steel ball bearing similar to stock, but for me it is equivalent to changing a timing belt.
Deep groove ball bearings are a standard commodity so one can be easily sourced to replace the one in the car. You will need special tools to remove and install the bearing as well as to perform fine adjustments to the valve timing when you are through.
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