I picked up my first Alex Singer (s/n 1477) from Spence Wolf's shop in late 1974. That bike was equipped with an Ideale 90 alloy rail saddle and a Campagnolo seat post, made possible by a set of what can only be called "adapteurs" that replaced the seat rail couplers (Campagnolo catalog ref. 698,699, 701 and 702). Spence had somebody fabricate these; maybe the same machinist that made his brake booster plates and "Alpine" derailleur modification.
One of these things broke on a ride and I limped home the last 10 miles with a wobbly seat. Spence sent me a complete new set of these parts. However, the bike was stolen sometime after that, 1979 or so.
The remaining 3 "adapteur" parts have been sitting in my junk box for 30 years. I knew that I was saving them for SOMETHING. I have never, ever seen another set of them!
Pictures on http://www.flickr.com/
Mark Petry
Bainbridge Island, WA