Metal Remodel box?

I need help from the pro's. I have a porch off the back of my house. The ceiling consists of TG 3/4 pine boards. Their are NO joints in this section of the ceiling namely because the run is so small. In essence I have a floating ceiling with no studs or joists to attach a normal circle box. I need a remodel box. However its my understanding because the wire that feeds the light is old 2 wire with no ground and is housed in flexible metal conduit. I need to use a metal box.

I see pictures of remodel PLASTIC boxes but have yet to see a metal remodel box that has the wings clips that grab on the backside of the sheetrock or in my case wood. Do they exist?

Yes they do, I have used them from time to time.Where to get them, try an electric supply house.

EVERYONE has them. Ace Hardware, Home Depot, Lowes, etc.

Pancake box

Can a pancake box be attached directly to a ceiling TG (wood)when hanging a pendent light and have it be OK from a code perspective. The ground wire screw would be screwed through the pancake box.

depends on how many conductors are going to be in the box