Missing pieces for Linhof Kardan Standard

I just bought a Linhof Kardan Standard with 2 lenses (135 mm f/3.5 and a 90 mm f/8) for $1400. The camera needs a rear standard with a ground glass and
a rail between the two standards.

I'm looking on eBay but I didn't find them. Can I find them new somewhere?

Another question.

Can we learn something with the serial number on the camera and on the lenses? Year of fabrication, etc.

Thank you for any answer.

Missing rail and rear standard sound a bit like you just have been ripped off.

Age of Schneider lenses is available here: http://www.schneiderkreuznach.com/service/serie.htm