Re: How critical is it to shim your starter?
Point a tooth directly at the starter drive spindle shaft.
Going with the flywheel/ flexplate, you want the drill rod to just slip in between the tooth and the shaft.
The starter drive gear will be back out of the way, so only the shaft it slides on is out that far.
Go with the flywheel teeth, and against (cross 'T') the starter drive gear spindle shaft.
Exactly 1/8" is what you are shooting for.
If the dust cover comes off in the right place, this isn't hard.
If it's way up in a bell housing somewhere, it's a B*TCH! With a capitol "B"!!
"I Have The Body Of A God... Buddha"