https://applink.reverb.com/item/5137725-1973-alembic-series-1-brown-natural
No affiliation with seller.

That's such a cool old bass... it was on here a few weeks back. The consensus was the price was a bit ambitious. Still... that is the definitive classic Alembic. 

Here's the Showcase Thread on #73-43:  http://club.alembicguitars.net/index.php?topic=8363.0

This popped up again on Reverb
https://reverb.com/item/13291506-alembic-series-i-lb-1
A really beautiful & classic early Alembic.

Just because my daily Reverb Feed told me the price ticked down a little bit, thought I'd dig back through and bump this thread...

https://reverb.com/item/13291506-1973-alembic-series-i-lb-1-w-ds-2-power-supply

Interesting the little things you notice looking closely at these early Alembics. Zoom in on the serial number of this one, and you can see it looks like it was first stamped sequenced as #45, then re-struck as #43. Here's why that's interesting to me... #73-45 is a small-body, walnut-topped guitar. (here's one of a few old threads on that one, that still has a working ebay link with pics: http://club.alembicguitars.net/index.php?topic=10659.msg123786#msg123786

And then there's the mystery of #73-44, which should have been right between them, but is missing altogether from the legendary posterboard. Go figure. There is a bass that fits in that slot with no numbers... but... there's no numbers. 

So is it possible the person stamping numbers in 43 & 45 had the #4 die tied up that day? We know they used all three numerals...