My brake lights aren’t bright enough

[hemifiedbird]

Your single filament bulb is probably your reverse lights

 

[1 Wild R/T]

Your single filament bulb is probably your reverse lights

No... 69-70 Chargers have little round lights in the rear valance for reverse lights... There are three red light sections per side, the inboard sections are strictly tail lights...

 

[Some Car Guy]

The 69 and 70 Chargers use a 3 bulb arrangement in each side. The left has an 1157 in the 1st and second socket and if I remember this right, a 1059 for the 3rd one. The right side starts with a 1059 then the 2nd and 3rd are 1157s.
The 1059s are single filament. They do not brighten along with the turn signals and brake lights.
To make these "Yorkim" bulbs work, I'd need a single filament for the inner sockets on both sides.

I see an 1141 can SOMETIMES interchange for 1059. You might drill into this deal or just give these a run for ten bucks. I do think they sell a few different styles of this one.