Greetings all.  I have a 2000 Z3 and have recently split the rear window due to age and temperature, I dropped the top on a cool morning.  Bav auto sells a replacement window but I am having trouble finding an upholstery shop that will install it.  (Bav auto recommends professional installation).  Any ideas or suggestions?  I really don't want to replace the whole top if it is not necessary.  Thanks