Maybe an old version of SPM?
I wouldn't recommend this: this would mean an old version of the template. Probably either MNI305 or Colin27.
http://www.bic.mni.mcgill.ca/ServicesAtlases/MNI305
http://www.bic.mni.mcgill.ca/ServicesAtlases/Colin27
You could also compute a downsampled version of the 1x1x1mm voxel yourself.
Why would you need this?