over the last few years have replaced the bakerlite thermostat housing twice due to cracks leaking. Rubbish part
I replaced the thermostat the last with pattern part as Ford did not have an orig in stock.
No probs for a few moths but then had leak again it transpired it was the rubber ring to the the thermostat this time
The pattern part ring is not as thick as the original, over time it also lost a bit of its elasticity so water started leaking past it

Moral of this use original part - thermostat and ring only costs approx £14.00