Ac compressor replacement questions

[Bgarza1122]

Hello, been trying to replace my ac compressor but ran into a question. Will the difference here not make it work? Or can I just find a way to hold the piece to the compressor? Old compressor turned on fine and clutch worked but mechanic insisted it was bad. Any chance he could’ve been wrong? original has 3 wires

[cory58]

Where did you get the new one? Did you specify that the old one is a Seiko? Over the years, E30s came with 3 different compressors. I don't think they are interchangeable.