Rad hose split

Hi, I been struggling for a few weeks now with a leaking hose and yesterday was the a major moment. I putting water in my car like it's going out of fashion. Done 6 miles and she was overheating.
Finally went and got her checked at the same garage that couldn't find the knocking prob. They said it was the water pump. But couldn't do it, had to be main dealer. One wasn't happy.
So took it upon myself to have a look and found a slit it the top radiator pipe looks like a 2 1/2 inch pipe. Its split at the top.
I have tried loads of garages and car parts people but can't get the part. Can anyone help with this.
On the pipe is a long number but don't think its a part number but it's GMDAT 96 942 184 PH. What to do????:confused4:

96942184 sounds like the right part number to me.

if you cant find one, match it up to one "off the shelf" im sure there is something close.