Nissen:s quality has fallen off a cliff of late it would seem. It's not the first time I've seen a post questioning their quality.
I'd heard the rad for the 306 was discontinued but there seems to have been a change somewhere along the line in design and quality....not entirely sure what changes, but something did.
To be honest, I'd look at a custom Ali job now. Somewhere between £150 & £200 will get you something very good that should last a long time.
Rallye .... On going OEM spec resto
GTi6 .... Weekend toy
Black 208 GTi
.... Wife's car now
Silver BMW 550i
.... The executive missile