that are generally parallel with the core assembly 22 third and fourth side members not shown are generally similar to first and second side members 26 28 but are generally disposed perpendicularly to the first and second side members to form the generally rectangular shape of the housing assembly 20 end caps 30 32 are generally perpendicular to the core assembly 22 to form the housing assembly 20 the side members 26 28 are attached to the end caps 30 32 with fasteners 34 a first seal 36 is provided at the attachment of the end cap 30 to the side members 26 28 and a second seal 38 is provided at the attachment of the end cap 32 to the side members 26 28 it is possible that the housing assembly 20 can have a configuration other than generally rectangular a collar 40 is disposed generally transverse to the core assembly 22 and separates the first or high temperature radiator 16 from the second or low temperature radiator 18 the collar 40 may be brazed or otherwise sealingly attached to the core assembly 22 and sealed to the housing assembly 20 to form a first cooling fluid volume 42 and a second cooling fluid volume 44 a first radiator inlet 46 to the first.