If the engine was installed in a vehicle with a Powerglide transmission, it had hydraulic lifters. Standard shift engines had solids. (At least on the early models). By the late 50's, I think all the engines were hydraulic. A simple way to find out is to find a valve in the closed position, and try to force the rocker arm away from the valve stem with a pry bar (Don't overdo it and bend the pushrod!). After a few minutes of continuous leverage, if the gap between the rocker and the valve stem increases to about 1/8", you've got hydraulic lifters. They bleed down when steady pressure is applied against the 2-piece lifter assembly. The lifter will pump up again as soon as the engine is run for a few minutes.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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