RPM-dependent gearbox whine
Well, since I know all the be-all, end-all people have spoken on the other forums, it is time to go this one alone. I put in a set of #8 primary chains and sprockets, taking care to not lose the chain's place on the sprocket (voodoo and probably not important) and also not lose the chain's location front to back (probably actually matters). I did the whole thing according to the fabulous primary drive swap guide posted here. I torqued (75 ft-lbs) and loctited/staked the new nut, I put the tensioner in right-side-up, and I put everything back the way it was supposed to go. Being able to do 70mph at 2500rpm is wonderful, yes, but now my gearbox emits an rpm-dependent whine that it did not emit before :x
The sources on Saabcentral did not say much of anything. Adrian (TooMany2cvs) thought I should look for things the chain is hitting, which was a step in the right direction. A post on Saabnet, though, revealed a bit of a surprise: the bearing in the top sprocket can go bad!
Here, then, is my chronicle of diagnosis and treatment of the stupid rpm-dependent whine.