318 + 904 question

I read from a poster, where.."68 318 and a 66 904 the snout of the torque converter is smaller than the register in the back of the crank. The solution is to have a bushing/spacer machined to properly align the two, spacer was 1.55" ID 1.81" OD and a half inch long..."

And another poster.."You also need the register adapter ring to adapt the 67 converter to your newer crankshaft..."

Are they talking about the same thing? Other than machining, is there some entity that sells these bushings/register adapter rings?

Thanks..