Bergwerks was Steve Linberg (and another guy)'s company and is no longer in business.
You can find a FGS on Ebay and it is made by a guy in Ireland. Coupe is his handle on Benzworld .org and I think he is a member here too.

Your 87 SEC should have FGS start anyway. here is how to check: First pull the shifter down to B(locked) at a light, then move the shifter back to D. When the light turns green, punch it and it'll shift through the gears as long as you dare to keep your foot in it.
The other way is to manually shift down to B, floor it, slap shift to 2 then 3 then 4.
IF you do not have 1st gear in either test then look under the car to see if the 1st gear solenoid is connected. it is on the passenger side rear of the tranny and is a one wire plug. My wire had been cut in my Euro 500 SEC.

__________________
1986 Euro 500SEC "RUF" 9:1CR, "Rose"
1985 Euro 500SEC Cabriolet AMG Widebody
1982 Euro 500SEL "Blue"
2001 Texas Heeler (Aussie/Queensland X) "Sulphie",
2012 Queensland Red Heeler "Squeak"
Best dogs I've ever had.