The following mold variations of part 3660 have been found so far:
The stud holes look bar-sized but they are still slightly smaller and do not allow inserting bars.
Types 1, 2, 4, 5 are shown in the photo below:
Type 3 is shown in the available colors on this page and in the photos by biodreamer.
Click on a colored part below to see the Sets and MOCs that use part 3660b Slope Inverted 45° 2 x 2 [Ovoid Bottom Pin, Small Stud Holes] in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.
There are 2 Mold variations of part 3660b - Slope Inverted 45° 2 x 2 [Ovoid Bottom Pin, Small Stud Holes] in the database, in use between 1977 to 1985. See Molds and other related Parts.