Hello Garvin 1,
If you are now confused on how to identify a solid or a hydraulic lifter in your 1956 engine,
don't feel bad because you are not the only one.
You were first told:
If the lifter has a snap ring at the top and a moveable plunger it's hydraulic.
That is correct.
Then you were told:
Most Sealed Power solid lifters have a spring clip- - - -
It's just the same hollow lifter body as the hydraulic ones have,
with a non-movable pushrod cup retained by the same spring clip as they use on the hydraulic type.That is NOT correct.
If your 1956 engine has solid lifters,
the lifters will NOT have a "Snap Ring" or a Spring Clip".
Here are some pics of lifters for your 1956 engine...
Hydraulic lifter 761 Sealed Power Hydraulic 761Solid 874Sealed Power Solid 874You can also "point to zoom" on the pics to see the difference.
Hopes this helps.