Slight beat note from Differential gear on VW1302

Air-cooled VW 1302 Super Beetle belongs to me has a critical problem on differential gear left side supporting bearing, though the symptom had been recognized when the procedure of trailing arm hinge bushes had been replaced. I was pretending as if I didn't recognized at that time, because the cause of slight rasping feeling was not determined whether hub bearing or differential side bearing when left side wheel were rotated by human arm intentionally. The beat note discerned while straight running on the highway has been increased these days, probably because the fitting on the drive pinion gear and the ring gear has lost with bad relationship between them, probably so to speak "Heel fitting condition", the left side bearing wear must be occurred inconveniently. Just replacing the side bearings on both side would not solve this problem thoroughly but following procedure would be taken along together at the same time, a very complicated and troublesome procedure, yes, fitting adjusting procedure to establish good fitting between pinion and ring gears in the differential gear box, otherwise, some strange noise would be carried out after assembling under difficult condition? The noise from the portion is not less so, a heavy duty task would be performed in very near future, a pair of rear hub bearings on both side are prepared already, additional order for diff. side bearing would be done ASAP. Otherwise, some hard metal dust from the broken bearing would do terrible harm on the trans-axle gear surfaces.