It very well could be the rear bearing...they sell a replacement kit part #
WE25M40 Also check the blower wheel to make sure it's in good shape and spinning true on the shaft. Make sure you check the front glides while it's open if they are worn down enough(gone) you can literally eat into the housing. Squeeking is an initial sign grinding is not good...if it's your rear bearing I would replace the front glides while your into it.