Hi my 70 challenger rt 383 has a bad oil leak, nor sure if its the rear end of the sump or rear main seal? the motor doesnt use oil? the car is covered in oil under neath. how do i find the leak? if its the sump gasket whats involved in replacing? or if its a rear main seal whats involved in relpacing? does the motor needro come out??
thanks all!

I changed my rear main seal with the engine in. I dropped the back of the crank just a bit by loosening all the main caps enough.

To help find the source, clean up the car so you can see where new oil appears.

My vote is tranny, too. Very common mistake. Dirt in the bell housing change red to mud easily...

Make sure it's not your oil sending unit,, they do that..

FYI, I have an issue that my transmission drive yoke seems to be leaking, as if it is cracked, or otherwise allowing fluid to seep through it. The seal is new, and dry, but the yoke can be wet at the U-joint, and fluid is on the transmission hump at that location.

yhe yoke has a plug in the end with a small hole ot let greese push out if it gets closed up a lot...it can blow that plug out also.

spay it down good with carb cleaner and use air hose to dry,then throw hand fulls of baby powder around suspect area of leaks.

this will slow it down and show right were its at.

check the low/revs lever pivot,you can see it at the back of trans just above the pan rail,the tail shaft has a nub that holds it from sliding out,the o-ring will leak and is ofter over looked when its leaking.

check the shift selector seal after cleaning with baby powder also

I would look at the oil send first thing to rule it out,could also be the end rails on the vally pan.

the rear seal retainers can/are a pain to seal up some times,use a good seal like one roadhazzed sells to get a good one,check the ends of retainer also to make sure they are in shape and line up.

good luck