Are those Shelley jacks? If so they were OEM in most British cars back in the 30's to 60's, I think. Some came with a three piece handle, but not folding - one piece has a rectangle end to fit the jack and the other end square shank, the end piece has the female square to mate and the other end a flat with a hole to accept the T-bar handle which is piece three. Shouldn't be too hard to fabricate one, I wouldn't think....