I put together a nice cheatsheet to help identify the right type of AL projector when you are looking at listings or out at a salvage yard.
Download the full PDF: AL Projector Identification Guide
You want to look for “Gen 2” projectors, they have the best optics and the wiring is simple. Gen 1 requires a solenoid controller for bi-xenon functionality.
Remember that aftermarket ballasts only run D2S bulbs. To use D1/D3/D4 bulbs you need an OEM ballast. D2S bulbs will fit in any of these projectors. The ones with octagon-shaped bulb holders might need a simple modification to allow them to take D2S bulbs. All of them with black plastic rings are designed specifically for D2S.