65 Dart GT Convertible

I am new to this group, so please bear with me.
I have a 65 Dart GT Convertible photo included.
I have a rear brake cylinder leaking. I think it is the original cylinder, l have included photos of it.
Is there anyway to really tell. I rebuilt it so those are the new dust caps on it.
Second issue my 7.25 rear end small drip from my differential cover appears to siliconed on. Any trick to remove it without bending it.
Thanks

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