Up for sale is 1 Nice New Old Stock Vintage Black Glock NY 3661 Trigger Spring with a leaf spring.
 
This was Glock's first version of their NY 3661 trigger springs. Not only does this one have a leaf spring, it also has the dark/black metal. When I checked my 1989 Glock Armorer's Manual, there was no listing for a NY Trigger Spring. But when I check my August 1991, it showed #3661 NY Trigger Spring. I have seen others with a brighter metal. I believe this to be the oldest version of the 3661 NY trigger spring. I have added a photo in this listing of how this was listed in my 1991 manual.
 
There is not a lot of information of this early Glock trigger spring with the leaf spring. I would guess these were made for the Gen 1 and early Gen 2 pistols.
 
This listing is for 1 NY 3661 Trigger Spring only, unless you choose the option to buy more by choosing more than one from the drop down box. 
 
The NY 3661 Trigger Spring shown in the close-up photos is one of two that are in the same NOS condition, you will receive it or the other one. 
 
Thank you for looking at my listing.