Installing salvaged old hardwood strip flooring

Q: I took out some old hardwood strip flooring from a renovation job and pulled out the nails from the back and plan on cutting out the damaged wood and re-installing the good wood in my home. I have put down a tongue and grove plywood subfloor and am wondering if finishing nails or using a glue would be the best way to install the old hardwood.

It is not tongue and grove, it’s simply strips.

A: How thick is this wood? If it is 3/4 I would consider putting a tongue and groove on the pieces or at least a groove on both edges and use splines. In that case and your initial question I would use both urethane adhesive and finishing nails.