So these algorithms are, being perfectly honest, not that great, they're high move count and a little bit awkward for grip, but they do have one huge advantage over other G-Perm algorithms that may make you want to use them, and that's that they only use R U F moves. No awkward Uw moves or ADF at the end. I found them myself so I don't know if there's a better one but anyways here they are.

Gc-Perm (start with headlights at the back): R U R' U R U' R2 F' R U R U R' U' R U' R' F R U' R'

Gd-Perm (Start with headlights on the left): R U R' F' R U R' U R U' R' U' R' F R2 U R' U' R U' R'

So if you do the algorithm you'll see its kind of like a Jb-Perm with extra steps. Not too difficult to remember I don't think. Unfortunately I got nothing for Ga and Gb but if you really like this alg then doing it lefty or lefty from the back is doable.