I have a 2008 1.2 pop and need technical advice if poss.

I think I have the following problem.
The exhaust manifold ticks for around 30 seconds from cold and then stops as the heat closes the (I assume) manifold crack. It's been like this a year or so (not got any worse), but as I am planning to sell the car it needs fixing.

So I have been looking around and keep coming across 2 different part numbers: 51864511 and 51938204

Just wondered if anyone knows will both part numbers fit? I am guessing the lower part number is likely the same as fitted to my fairly early 500.

Thanks

Look for signs of leaking black sooty deposits if there's non leave alone ticking as it cools and in fact the whole exhaust is quite normal so unless it's clearly faulty don't fix as the part is likely quite expensive, and the fitting of probably not easy due to seized bolts