First, my truck is not a "Pickup", it is a GMC 3500 HD Commercial Box Truck.

What is your question?

My truck (as listed above), would not start, even though it had power. Check Starter, relays, and fuses. Replaced Starter, still the same, checked fuses again, no fuse listed 'Starter" but found one listed "Crank", it was blown, I replaced it (10 amp), truck started as usual, then started blowing the same fuse repeatedly, and now cannot be cranked at all without blowing the fuse immediately.