I have a 97 cummins and it want charge the battery, the altenator checks out fine, the y say it a crank sensor if so where is it located

Check the starter. If your power supply (battery) is fresh and healthy, then a slow crank can really only be caused by a failing starting motor.

what you need to do is check the altenator for voltage it should be between 13 and 15 volts this is easily done with a standard volt meter check it at the altenator witch is located right on top of the engine on the back of the altenator there is a thick red wire that is where you want to put the positive and just put the black wire of the volt meter on the case of the altenator and check the reading it sounds like the altenator is bad there is also a fuse you should check your owners manual for location of the fuse also have your battary checked this should help ant questions just ask me

Check altenator to see if charging.
Check fuel pump, replace if needed.Check Throttle positioning sensor, replace if needed.

sounds like a injector pump to me had a 99 dodge cummins went through three of them in 350000 miles done just like you are describing.

check and make sure the powrr wite has a solid cconnection the check the grounds to the starter.

if its a 5.7 change your distributor cap and rotor and problem will be solved guarantee it

check the voltage regulator or any relay that connects the alternator, including the fuse.

I had the same problem on a 94 dodge with the cummins. It seems the crank sensor that reads from a notch on the harmonic balancer was the problem Without this sensor reading that the engine is running the alternator wont charge. Possibly the same problem with yours

run the fault codes
check for problem MAF?VAF sensor and accelerator position sensor

On an American designed charging system the truck should remain running, on Japanese cars it will die, but to anser your question yes you almost surely have a defective alternator. Make sure the battery is fully charged before the new Alt. is installed, if you don't the new Alt can be overheated and damaged.