Please don't call these "zip ties"
. That is a term for the things we use today almost like we use duct tape. I don't recall the term we used for these back in the day, but I'll just call them straps.
Below are the 4 locations on my '69. They may have migrated a bit from when the truck was new though. Note that, at least on my truck, the passenger side straps were black, and the driver side were white I have no idea why. Size differentiation? Since this is an early '69 the washer bottle is on the core support, and the hot water shutoff valve is different from a '72's. I won't be able to look under the dash for a few days.
Please ignore the two 12 gauge red wires in the passenger side photos. I ran those to supply 12V to a 3-way camper refrigerator.