Recently purchased this beauty from another member here.

The serial number appears to be 853115 USA.

This bass has the tone I have been searching for.

I love that bass, congratulations!

Thank you. I've been searching for this tone for years.

Wow, tough one! :-)

That's an early '84 number, truss rods cover is also 84 style.
Though everything is possible with Alembic, most common sizes for those covers are:

Very small with squared edges until about '83
Slightly larger (like yours) with squared edges in '84 (maybe also late '83 and/or early '85)
Again slightly larger (same size as what's standard now) with squared edges in '85 (maybe also late '84 and or/early '86)
Modern style, large with rounded edges on fingerboard side since '86 (maybe also late '85)

And that's clearly a 5, not a 4... :-)
So maybe "finished" in '84 and the customer wanted some extras which took it into '85?
Also looks like there was some restamping done, double 8, maybe double 3, double 1 in different fonts (?) and double US.

Subscribed! :-)

Awesome bass!
That's a custom variation of the Spoiler body, or maybe somebody slipped and bumped the lower body portion when they were being glued up. 
Anyways, almost get Scorpions vibes from that more symmetrical look. 
And that's a Series II style neck, one more cooler than Series I innit! :-)

Congrats and enjoy!

😃
It's the one with the whammy! 

Welcome to the camp Thomas!   

Good for you! Enjoy the bass!

Mike

Nice.

That's a very cool bass, congratulations! 


...and I like your in-ear monitor

The bass stays in tune as well as any of my other high end basses, even with the tremolo.

The tremolo is fun to dive the E string to the depths of the earth, on occasion

Update: we played our first "post-COVID" show (I'm not really sure that COVID is in the past, but that's a different topic),
and I'm very pleased to find that a bass guitar with a Kahler tremolo will stay in tune for a 15 song set!

Yes: a 38 year old bass guitar with a factory installed tremolo stayed in tune perfectly.

😎

I'm also curious about the S/N being double struck, it is an interesting quirk.

We dug up some more photos of #853115

I'm still looking for this file. As Flip said, the sequence isn't quite right, and that stamping looks a fright! I see the two different fonts, and that's a little concerning since we only have one set of numbers. The 1985 numbers start at 3449. I'm going to pull that 3115 file and see if it matches here and what is going on with the numbers adjacent to it.

Regardless, it's lovely and I'm glad to hear it's satisfying your tonal needs.

Hey Mica - here's a clearer picture of the serial number I took while I cared for it.