Montgomerie finished with a birdie on the par-4 ninth hole at Fallen Oak. The Scot won the Senior PGA Championship and U.S. Senior Open last year.
The players faced 10-20 mph wind out of the northwest with stronger gusts.
''This is a mere breeze where I'm from,'' Montgomerie said. ''Five under par is a good score today. Anything under par is a good score today with very testing conditions. Every shot today was different from yesterday because the wind was completely different. This is a very, very good course, perhaps the best we play on this tour, and it's even more challenging in the wind.''
Durant also closed with a birdie on No. 9. The four-time PGA Tour champion is winless on the 50-and-over tour.
''The wind was tough out there,'' Durant said. ''It was swirly and gusty, but if you can put the ball in the right places on the greens, you can make some putts. It was a good test today.''
Durant is playing in this event for the first time, but his resume includes a win in the 1996 Nike Tour Mississippi Gulf Coast Classic. He grew up in nearby Pensacola, Florida.
''It's nice to only be a couple of hours from home,'' Durant said.
Fred Couples, the 2012 champion, had a 71.
Jeff Maggert, the winner last year in his tour debut, shot a 73.
Miguel Angel Jimenez closed with a double bogey for a 76. The Spaniard won the season-opening event in Hawaii in January for his second victory in three career Champions Tour starts.
Jesper Parnevik also struggled, making a triple bogey on the par-3 third in a 76. He tied for 42nd last year in Tucson in his Champions Tour debut, shooting 71-74-71.