T3 Timing System Life

[n3303j]

My '77 850T3 has 100K miles on the engine with the original timing gears and chain. It has 70K miles on the new style bow chain tensioner.

I'm starting to hear a bit of a rattle from the timing chest. Should I just replace
A. Tensioner.
B. Tensioner and chain.
C. Tensioner, chain and cam sprocket. (BMW choice)
D. Tensioner, chain, both sprockets.
E. Ignore the rattle and get better ear plugs.

[guzzisteve]

Just the chain, it'll all be good for another 100. Sprockets last long time.