[Mike Taylor 3601]

Some good tips here,cover all the basics first.. ''l add....flexplate straight and round...,bolts are knurled,but are they tight in starter....,there are few different sizes.... that flywheel and drive may never be made quiet once it has been roughed up...

The best way I have found to fix noisy starter is install it without the solenoid,so you can engage the drive into the flywheel and check how the teeth meshing...use pliers or needle nose,to turn the drive and check backlash... worst one I ever fixed,I had to mill the nose about .075'' to get teeth deeper...
fit it to where teeth are meshed so they almost bottom out,but you still have a little backlash,can rock the gear just enough you see it has clearance
you will see a huge difference in how the gears work when properly meshed,takes way less effort to turn