drive shaft lenght

In the last month I replaced a questionable harmonic damper, reshimmed the rear axle for less pinion angle, checked runout on wheels to make sure axles were straight (they are), and yesterday revisited driveshaft again cause every time I “touch” anything with the driveshaft the issue reduces… or moves up to higher speeds…. We are now up to 50 mph… we used to be anything over 20 mph… length is where I am now… and verified that I got it wrong, so as to get any doubt out I’m not reusing any of it (it’s all 7260 joints anyway) and I have a 340/727/8-3/4 sure grip 3.91 gears. Going to go ahead and step it up to 1350s (conversion cross at diff until I decide how to change a yoke on a crush sleeve unit (another problem for another thread).

But here is where I made it to the “Regret Phase” of the project where I regret reusing anything now that I’m way too many dollars into it already and have an unenjoyable, vibrating pita to sort out… and every question that could pinpoint where to even look is “yes“….

A lot of factors for deciding driveshaft length, U joint needs or wants is another factor. Just cause you have a good part doesn’t mean you should reuse it for your build, might be fine, but may not be preferable in the future direction your build goes.