In order to determine if the engine came with mechanical or hydraulic lifters, you need to decode the Engine Serial Number that is pressed into the block behind the distributor (as described by Mike). That code will show if the engine was installed in a truck or in a car.
All 1956 and later 235 car engines came with hydraulic lifter.
All truck 235 engine came with mechanical/solid lifters.
1957 truck ESNs1957 car ESNs
