As my MK3 was partially dismembered when i acquired it and the battery side cover was "off", so it has taken several months through elimination to discover was the small "stainless Steel" ????? support arm was , and now i know... Side cover support.. The fittment as i have it must be wrong or something missing... On the support arm that is bolted to frame it has a rectangular hole in it, which appears to be of factory quality, but to two small holes 1/8"dia that had pop riverts "ground off" with a plug of rivet trapped in the holes, which were removed prior to powdercoating.. Which make me thing there is a bit missing.. I have trawled through my available references books but none show the side plate "locking mechanism" in detail.. Can somebody guide me to a reference source or post a picture.. The correct terminology would help me search also.. Thanks........