kip,
if I am not mistaken,the pushrods used with hydraulic lifters are hollow and they have holes in the ends to allow the oil to flow through. The pusrods used with solid lifters do not have the holes. The top of a hydraulic lifter reveals a cup shaped disc held inside the lifter bore by a small snapring. On the other hand the solid lifter has a concave top that is mounted on top of the lifter body.
