1 - You have a tag on the door frame/pillar...have a look at it where it says "axle/trans" or similar, and read what it says.
Read these links to figure it out...
Diff page 1
Diff page 2
2 - Does it puff blue when you step on the gas after coasting down a long hill, or puff when you start the engine? Do a compression test and record your numbers. Do it again, but put a squirt of oil in each cylinder before cranking to test, then compare numbers. If the latter set is higher, your rings are shot. If not, it's most likely the valve seals leaking.
Read these links to figure it out...
Diff page 1
Diff page 2
2 - Does it puff blue when you step on the gas after coasting down a long hill, or puff when you start the engine? Do a compression test and record your numbers. Do it again, but put a squirt of oil in each cylinder before cranking to test, then compare numbers. If the latter set is higher, your rings are shot. If not, it's most likely the valve seals leaking.