I recently swapped my 72 Duster rear end to a 8 3/4 with 3.55 gears. Everything within the rear end is new except the gears. The gears were in good shape so we reused. When accelerating and you reach 50-60 mph a howling noise can be heard. Only when accelerating and only in this mph range. Is this a shim issue due to the old gears being used or is this something I should be more concerned with? Thanks