Cranking problems. Would like to know troubleshooting ideas?

This is a pretty vague question. Trucks this old have all kids of possible issues. Not only component issues but wiring/corrosion issues. Start with the basics. Get the battery tested and keep your eyes peeled for green/yellow corrosion on the terminals. The starter OR the cable running to the starter could be faulty. With a faulty fuel pump tho, it may not start at all. I've seen LOW fuel pressure to all out dead pumps. Without actually seeing it or more details - that's as far as I can go for now.