Can the Crank sensor be changed without removing the balancer? Factory service manual states to remove the balancer. I can get at the two bolts holding what looks to be the sensor, or at least where the connector plugs into, but I do not believe it will be that easy. I havn't tried it yet.
GM part# is 12537111

Any thoughts.

No experience with the 3800 Series I; however, on my Series II, you do need to pull the harmonic balancer. Go to AutoZone and rent a harmonic balancer puller. You'll have the sensor changed in under an hour. Wish I could give an authoritative answer, but I hope this helps.