@Vinson777 , Yes it should work fine from a storage perspective - the only thing that could feasibly impact storage availability when using mixed builds is if there has been a change in the On-disk format (e.g. 6.7 GA vs 6.7 U3 and changes made to Disk-Groups), but there is no such change between the versions you mentioned. Additionally I am not aware of any EVC-affecting CVE-related changes in the interim of these builds (none require EVC since Spectre-mitigations IIRC).
That being said, as @CyberNils stated, you should update the remaining nodes to the same build for consistency and to avoid any potential issues with running on 3 different builds (unsupported) when next updating these nodes (e.g. if you don't get them onto the same build now).
