Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
This is not a job for the average mechanic, since there no marks on gears or chain.
There are special tools to lock the crankshaft and camshafts in the correct position.
The cam phasers have no dowels or keyways.
If you want to replace just the the chain and tensioner assembly, you could mark the sprockets and chain with a paint marker and mark the new chain in the same format, then replace the necessary components.
I have worked for GM for many years and I would not undertake this job, unless I understood the risks involved as I have mentioned.
Have you had a quote from a GM dealer to do this for you?
I hope my advice has been of assistance to you.