WS-C3750-X stack

I have two ​WS-C3750X-48T-S and one ​WS-C3750X-24T-S switches.
Two 3750-E now work in the stack with
System image file is "flash:/c3750e-universal-mz.122-52.SE/c3750e-universal-mz.122-52.SE.bin"
And new 3750-X with Universal NPE IOS
System image file is "flash:/c3750e-universalk9npe-mz.150-2.SE4/c3750e-universalk9npe-mz.150-2.SE4.bin"
I think I must use same ISO version in all swithces, but I not found NPE ios for 3750-E