here we go again--frame numbers

[kwmech]

Did a search and a lot of reading. Short story, I managed to find a 68 lonhorn a few years back at the wrecking yard that was on its way to be crushed (2 days later) whew that was close--anyways I hauled it home. (minus paper work at the time) . I am about ready to start it up and run it---still no paper work. After bugging the owner of said junkyard for the last week he says he's having trouble finding the 'correct' paperwork and wants the numbers off the cab and frame. No problem with the cab--but I can only find 4 characters off the frame--all I've got are 8Z87. I've been up and down both sides top and bottom. Any other hints? frame rail part numbers I'm assuming 3941617 104 416 36 on the left side and 3941618 104 416 36 on the right.


edit: the 8Z87 was found on the drivers side next to the motor mount stand