The chain in the Challenger transmission was still with in the factory wear limits
but elected to change it and the seals since I needed to replace the output shaft
seals and knowing the Challenger would be using a modified engine and driven
to its limits I wanted the gear box to be as reliable as it could be.

I got a chain from Bill Keefe, it is a O-ring chain pressed together and uses no master
link, I have heard there was problems with oil affecting the O-rings and since the chain 
is in a closed case and running in oil they really are not needed, you can buy a much stronger
chain by getting a O-ring chain, I spent about 1/2 hr and using a pick removed all the O-rings
not the chain moves freely like a non O-ring chain.

These transmissions are a great little and very tough gear box they require very little maintenance
and will take all kinds of abuse, you can see in the picture below when the chain gets stretched
it can actually make contact with the cases, when the chain breaks it usually makes its own 
exit from the cases leaving you with a pile of junk. Check yours make sure the chain cant touch 
the cases like the blue arrow.

A close up, Inspect the sprocket teeth (pink arrows)

With a new chain installed you can see it does not even come close to hitting the cases, like a 
engines compression I will check the wear of the new chain as outlined in the service manual 
once this box is installed and record the amount of slack in the chain, after each long weekend
of riding it will be measured again this way I can keep track of the chain stretch and know when
it is time to replace the chain again.

All these gears will be removed, the gaskets and seals removed, everything washed, new seals
and chain installed, there is no visible wear on this transmissions internals other than the chain
found so far.
More on transmissions later