everyone knows the best do-nuts to get are the fresh ones! (maybe you had the old batch, 'cause fresh ones normally span years of use)

...the install should definitely not take an hour (unless there was a lot of focused drinking, socializing, and gabbing going on)...and a tech with minimum skills should be able to do this blindfolded and drunk in 15 minutes

...on your install (open your beer), support the exhaust system using a wooden block and your garage jack- lifting the exhaust as close to the undercarriage as possible

take a swig of your beer (or beverage of choice)

work on one hanger at a time:
remove one hanger, using leverage action from a long screwdriver- take another swig- pick up the new hanger- take another swig- - muster up a big piece of spit in your mouth and let it fly targeting the inside portions of the do-nut in your palm- - - another swig- - and slide the first side on then use that leverage action again to get the mating piece attached (you may also optionally shoot a few higher lubricity loogies over to the exhaust mounts and chassis mount points to aide in the lube process- do not use a lube that attacks rubber)

repeat the above till all the do-nuts have been replaced moving the jack and wooden block to the most appropriate lift points to close the gap between the exhaust hangers and mount points

oh, take another swig....and enjoy - - and - - make sure that any 'hard mounts' of you exhaust system are also in operation (ie your system may also use some type of metal bolt(s) to a chassis mount (for support) so the rubber do-nuts are not accepting 100% of the exhaust system weight- may be cause premature do-nut failure)

have a great day
-fad

PS- if you're ever near SF, CA- I'll install these for you for half of what your last labor bill; bring the right parts- no need for appointment - and I'll have you in and out in less than an hour