The old yellow handled automotive crimpers are NOT the ones you need for this job. While you are at it, order a couple hundred pins and re pin the entire backbox, .100s 156s all. You will thank yourself later.

Also, to save some money, the shells need not be replaced 99.999% of the time, just re-use the old ones. And, a pin tool is not needed for removal, just a small screwdriver in the slot, push down and pull.

Pro Tip: Don't try the rookie move of trying to sand either the headers, or the female pins. Might work for a week, then you're back to square one.