LOL im confused u getting a nitro or elecy?

Locking the diffs is up to you m8 try it without first and see how you go i tried locked rear and went back to both open it depends on your tyres more i think and you can always unlock them if you dont get on with them being locked [8D]

Not sure about the Red cat lightning diffs but u just open them up and use something to lock them ie blutac,balls of paper etc i wouldnt use strong glue incase you decide to unlock later on.