Found this to be very informative, great section on rust in the tech link. There's a resto 23window in there for you Rob K

http://www.busbones.com/contents.html 

As a point of interest, Kevin Murray the owner of Busbones ripped me off when I was working in the US. Sent him money for 23 window bits and he never delivered and left a trail of BS a mile wide when I started chasing him. I returned to Oz and never really had any recourse once here.....he must have promised to send a cheque/return my money a dozen times.....never quite got around to doingit but.

Wasn't an absolute fortune but it was certainly a lot more than we could afford to give away.........