That's a pity, I know one of the overhead railway carriages is in the Museum of Liverpool but as a kid I remember the (world) Museum also had a number of trains on display but have no idea if any of them are still there since the museum was updated. Doesn't seem to be an accessible area anymore.
So is the old stock not being used anymore? It's the first time this week I have been on the new trains to and from work this week.
I was on an old 6 car on the Hunts Cross line this morning and yesterday - getting rarer but still running at the moment