After researching alot of photos, downloading and doing some side by side closeup comparison, I finally got my answer. Unfortunately not the answer I was hoping for. I'm a bit disappointed. I was so sure it was the same truck.
The Toyata Landcruiser used in 50 first dates is not the same as the one used in Lost Boys.
But there are subtle differences I noticed. The truck in Lost Boys has a flat grill and orange marker lights under the headlights. While the truck's grill on the one used in 50 first dates is slightly rounder and missing the marker lights. I also notice gas tank access is different on the two trucks. And I can't be positive, but I think the lost boys truck is a 1971. And the 50 first dates truck is a 1970. Neither one of then is a 1968.

It would depend where the scenes of 50 First Dates with the Land Cruiser were filmed. Most of the movie was shot on Hawaii I believe, and I doubt that they would import a Land Cruiser for the movie. There's also the 17 year gap between the films.

Maybe it's this one: http://www.cinemavehicles.com/store_inventory_categories_details_print2.asp?id=3- 090

We also have:
http://www.imcdb.org/vehicle_126521-Toyota-Land-Cruiser-J50-1968.html
http://www.imcdb.org/vehicle_195704-Toyota-Land-Cruiser-J50-1968.html
http://www.imcdb.org/vehicle_196205-Toyota-Land-Cruiser-J50-1968.html
http://www.imcdb.org/vehicle_268906-Toyota-Land-Cruiser-J50-1968.html
http://www.imcdb.org/vehicle_305094-Toyota-Land-Cruiser-J50-1968.html
http://www.imcdb.org/vehicle_337339-Toyota-Land-Cruiser-J50-1968.html
http://www.imcdb.org/vehicle_435223-Toyota-Land-Cruiser-J50-1969.html
http://www.imcdb.org/vehicle_339560-Toyota-Land-Cruiser-J50-1976.html

All of which can be that vehicle.

Here's Grandpa's truck:
http://www.imcdb.org/vehicle_41949-International-Harvester-M-2-4-1942.html
And the others:
http://www.imcdb.org/movie.php?id=93437

The Land Cruiser is the same kind, and the same colors, but I don't know if it's the same truck:
http://www.imcdb.org/vehicle_3398-Toyota-Land-Cruiser-J50-1968.html
http://www.imcdb.org/vehicle_6064-Toyota-Land-Cruiser-J50-1968.html

Hi
Can anybody tell me if the 1968 Toyata Landcruiser used in The Lost Boys is exactly the same truck as used in 50 First Dates?
Also does anybody know where Grandpa's car is now? (from the Lost Boys)?
Been dying to know the answer to these two questions so please help
Thanks xx