UE2.5 upgrade to 64bit

We are servicing under a full license of Unreal 2.5 version 3369 and use 32bit.
I’m having a memory problem, so I’m going to upgrade to 64-bit.
I know that Unreal 2.5 supports 64-bit, is that correct?
I searched the code but couldn’t find any 64 bit related code.
Is Unreal 2.5 divided into two versions, one for 32-bit and one for 64-bit?
can we get a 64-bit version?
It’s possible?