Lol, I wonder that about XUD blocks....they'll run out eventually with the amount of rods that go through them. 
The chassis' will have rusted away before the engines run out though. 
I think my 'advice' was taken a bit too literally if I'm honest, yes I'd rather swap an engine than a belt one these, quicker, safer and cheaper for me...that's my opinion, not fact. The fact was that I've never seen a 306 HDi snap a belt through age so wouldn't bother changing one that's been changed fairly recently... I changed a 90k one and wished I hadn't because it was still perfect, rollers didn't even need changing though I obviously did the whole kit anyway. Was a lot of hassle and expense to go to for something that looked as it'd come off the production line. The HDi's don't put much force through the belt (as standard at least) and don't forget it's sealed in the covers as well, not like an aux belt or tyres that go through water and salt and all sorts of crap on a daily basis.
The chassis' will have rusted away before the engines run out though. I think my 'advice' was taken a bit too literally if I'm honest, yes I'd rather swap an engine than a belt one these, quicker, safer and cheaper for me...that's my opinion, not fact. The fact was that I've never seen a 306 HDi snap a belt through age so wouldn't bother changing one that's been changed fairly recently... I changed a 90k one and wished I hadn't because it was still perfect, rollers didn't even need changing though I obviously did the whole kit anyway. Was a lot of hassle and expense to go to for something that looked as it'd come off the production line. The HDi's don't put much force through the belt (as standard at least) and don't forget it's sealed in the covers as well, not like an aux belt or tyres that go through water and salt and all sorts of crap on a daily basis.