Question about tripod mounting plate...

[PelaPapas]

I have a Manfrotto (Nikon?) #390 tripod. It's missing the mounting plate. I'm wanting to use my spotting scope and bino's on it. Would I be able to find a universal mounting plate or would I need to specifically buy a mounting plate for this exact tripod model?

[Eagle Eye]

You can buy them at sportsman warehouse for like 20 bucks. I actually have an extra that I could sell