Yes, I did have the same codes prior to tach install. I think I read somewhere that the codes should be numericaly sequential but in my case 45 always displays before 41.
I was very careful to not short anything. The tachometer is an inexpensive thing I got on Ebay. Digital RPM TACHOMETER with Built in Warning Light made by Type R

wannadiesel, I want to thank you for your many excellent posts.

1993 W350 DRW Auto, AC

 

It's not surprising the tach isn't working, most tachs don't like the signal that the PCM puts out.

The codes point to an alternator or wiring harness problem. Check the harness where it runs across the power brake booster and firewall for any chafing. Otherwise it's probably the alternator itself.

The crank sensor is not the problem here.