What rad do I need?

[C8LE_M]

We have a 1.4 auto mk1 without aircon, and I'm pretty sure the radiator is knackered, but looking on ebay for a new one, i find there are 2 types. They tell me its all about core size? Wtf is that? Can someone tell me what i need to ask for please
I can provide a reg number via pm if it helps ;)

[Mickswan]

Try euro car parts, pop your reg in and sorted.

[C8LE_M]

Cheers fella, that gave me the dimensions and I found one on eBay for £26! Bargain!