About 8.1 in 6.0 yes you can but 6.0U3 only. For this I recommend you to have always at hand the Compatibility Matrix website VMware Product Interoperability Matrices
I did not found details about that two versions specifically, It should work I think, but in my experience I would recomend that you upgrade and have the same version if possible.
Please refer following information:
1. vSphere replication should be running on identical versions across sites. If you have source VR at 8.1, then the destination VR should also be running on 8.1
VMware vSphere Replication 8.1 Release Notes (Please refer note under installation section)
2. vSphere replication 8.1,8.1.1 can be deployed in vSphere 6.0 U3 and later versions(Upto 6.7 U2. 6.7U3 and later would require 8.1.2, 8.2, 8. versions).
I hope that helps
Hi, sorry for late response.
I think i must try it in my lab to prove the document statement.
Thank your for your advices. It help me a lot