found a 2001 LT for sale so i took the number and called, guy i talked to says it leaves a small oil mark under the rear of the motor the size of a palm print on the garage floor. he is aking $2,000 and it has 168,000 miles on it, this thing is super clean, can you give me an idea of the usual trouble spots to look for

 

I had a slight oil leak at the back of my '00 Bravada. It ended up being loose oil pan bolts. With those kinds of miles on it, it could be a rear main seal which would be the worst case scenario (just so you aren't caught off guard if this is what it is). It is also possible that there is a leak at the oil pressure sensor port on the top of the block to the driver's side on the back rail. Another problem spot on these engines in 4wd applications is the crimp on the oil lines, but this wouldn't be at the back of the engine unless something is leaking from where the lines attach to the remote oil filter adapter.

So I would recommend you check the torque on the oil pan bolts. If that doesn't cure it, you'll want to check the back of the block up top. If you still don't find signs of oil and you have 4wd, you'll want to check the lines and remote oil filter adapter on the driver's side of the block above the front differential. Still don't know where its coming from, you'll want to pull the plugs out of the bottom of the transmission bell housing to get a look at the back of the engine. If you see oil on the front side of the flex plate, you have a rear main seal leak.

 

Just to add to Kyles' list, it could possibly be from the rear of the intake or the back of a rocker cover gasket or distributor base gasket and leaking down the back of the engine.