The early small six's with the solid/ mechanical lifters, oil to the lifters were different but the later hydraulic lifter blocks all oil the same. Cam bearings and oil to rockers oil the same. No cross drilling, that is why the rear cam journal is grooved.
The lower part off the dist. shaft fits in the block and keeps the dist. gear form flexing away from the cam gear. The block its the bearing surface and it is oiled by a 1/8'' drilled hole to the first oil passage from the pump to the oil filter, and without dist. shaft in place will cause an good sized oil leak.
The lower part off the dist. shaft fits in the block and keeps the dist. gear form flexing away from the cam gear. The block its the bearing surface and it is oiled by a 1/8'' drilled hole to the first oil passage from the pump to the oil filter, and without dist. shaft in place will cause an good sized oil leak.