Early hull numbers were not equipped with a topping lift.  They can be easily installed however choosing from a variety of methods.  Catalina has prepared the 250 boom for running one internally.

There are many ways to rig a topping lift.  They may be fixed but are more often adjustable.  While some rig them in a halyard form using a block on top of the mast, most sailors avoid another line slapping the mast and rig a fixed segment from aft on the mast truck to near the aft end of the boom.  There, a block is attached.  A  line runs up from a secured position on the boom end up thru the block, back down thru the starboard sheave on the boom end, forward thru boom and over the starboard sheave.  From there, it will take either of two directions.  If reefing is to be done from the cockpit, the topping lift line should also be led to cockpit, run the line down to mast base and turn it back via deck organizer and clutch.  If however, lines are not led aft and reefing is performed from on the coach roof, then the topping lift should be routed back thru the boom after leading over the starboard sheave and exit the starboard side just as the outhaul line does to port.  A clam cleat should be provided.

If trailering, a snap hook can be made to the the fixed topping lift section to snap to the bail of the small block.  If the boat is slipped or moored, secure the block to the fixed section of line from the masthead with a bowline knot.

Some prefer a very light wire line from the mast head, sometimes with a plastic covering.  A quality 3/16 line as the fixed line from the masthead is adequate.