radiators on 1995 Ford E-250

i got a 95 ford e 250 van 4.9 straight six in the past 2 months ive put three radiators in the truck and now my fourth one has blown they keep blowin out at the bottom seems the truck dose not over heatis this commen in these trucks or could i be havein too much pressure in the truck can someone plz help me on this

Asked by for the 1995 Ford E-250
Has the radiator cap been replaced? Has the truck been in an accident making mounting the radiator stressed? Lastly have a "block check" done it is a chemical test done to look for the presence of carbon monoxide in the cooling system which would indicate a "blown head gasket" which would increase cooling system pressure.
the block has been checked and is not cracked its never been in a car carsh after the 2 one had blown i did replace the cap
2 more answers , 1 more comment
How about the presence of voltage in your cooling system? I suspect you may have electrolysis - which is when current in your coolant causes welds in your heater core or radiator to fail and cause leaks. Put a voltmeter in the coolant and see if it is conducting electricity. Ground straps, a solid flush of the cooling system - might be in order.
Get it checked for a cylinder head gasket leak. It could be letting exhaust gasses into the coolant raising the pressure. Have you installed a new radiator cap with each radiator? If you have been using the same cap from the first blown radiator there is a chance that the cap might be causing the over pressure. But I would tend to think head gasket.
i have not tryed a new cap sense the 2 one blew on me could it be a bad clutch fan causeing this also possibly? i also noticed u were talkin about the exhaust i have a exhaust leak on the truck could that play into the problem