Is it possible to source/replace a single corroded rear light bulb holder or do you need to buy the complete loom?

 

Thanks, Ben

That'll clean up, all you need is is mini wire brush in a dremel to polish the bits that make contact, the rest doesn't matter.

Once cleaned up smear all contacts in vaseline and this should be good for many years, always did this with my car and holders are like new many years later