Merryweather Gang Attack (solo):
L82 Character (minimum is L18 I think)
Invite-Only Session (but any private session should work)
I arrived at the beach just before 20:00, but I guess it's there until 4am.
One thing to note: I could not store it directly in my garage. On my way home I stopped by LSC first and tracked and insured it. Then when I got my garage, I got the "this vehicle cannot be stored". Since my character is set to start at home, I just exited the session to SP, then got back into another private session. And there it was as seen below.
UPDATE: I can drive back into my garage with it. Freak glitch maybe.
The 'Jurassic Park' schemed one (open top) I've had it for awhile now. I airlifted it out of the base during 'Base Invaders'. Also acquired solo. (it helped that my garage at the time was the 6-car just up the road from the base)
I only mention it was Solo so you don't have to wait to drag a friend along.
Map: (from Google)
I found two hard-tops out there:
And safe at home: