garretthes,
All 235/261 truck USA engines (through 1962) had mechanical/solid lifters. V8 truck engines had hydraulic lifters.
Automobile 235 engines with Powerglide transmissions had hydraulic lifters starting in 1953. I am not sure about the lifters in standard transmission 235s in automobiles from 1954-1962.
I think there was a 261 engine in Canadian Pontiacs that had hydraulic lifters.
In the Tech Tips section of this site are a couple articles on adjusting 216/235/261 lifters. Here is a another link on
adjusting valve lash. Tim
