Joe, I know how you feel. It seems like making friends is so much harder now that we're older. A lot of "my" friends were the men in the couples we used to socialize with, and it's hard now not to feel like a third wheel when we get together.
Something that I've found, though, is many of them are in the same boat, wanting some male friends they can hang out with, and all I really have to do is ask if they want to get together. One even pulled me aside and said "You know, I've been thinking... I don't really have any just "guy" friends. Give me a call and lets get together and do something."
Another thing I've been doing, is there are single guys that we knew, but weren't close with, because we didn't really get together because we were doing things with other couples. I've been reaching out to them, and they've been great.
Like Fast Cars said, I am finding group activities helpful to meet people, too. Both men and women. I've heard both good and bad things about meetup.com, but you might want to look up similar groups online in your area. You're sure to find some people with common interests. Most of the bad I've heard is from women who complain that men are just using it to pick up women.
M:23 T:26 Me:53, Wife: 60 S:18 D:16 filed 7/16 W moved out 4/28/17