AS title says I have developed a rather sudden oil leak at the lower rear in the engine of the car, I'm hoping its only a sump gasket and not a rear main seal. The leak only came to notice after giving the car a little play then after stopping I could smell oil and there was smoke coming from underneath. When I looked there was oil around the front of the bell housing droping on to the exhaust explaining the smoke. I havent been game to look yet but if it is only the sump gasket how hard is it to replace.

not to hard, drain the oil, unbolt the sump. remove the old seal/gasket thats stuck to the block and sump, put the new 1 on and bolt it backup and fill her up with oil again.
mite wanna put down sum old carpet or something to catch any dripping oil and wear old clothes coz its a garuntee that ull get oil on em

it's a C*** of a job, you have to either drop the k frame or lift motor up to do it properly.
i've done it it a bit dodgy before in an EL V8, just dropping sump onto k frame to get the bare minimum of room, then using a felpro 1 piece gasket, cutting it to get it on, then putting a dab of sealant where it had been cut (around the front moon).
it worked/is working though, but i did it properly and lifted the motor in my ED.
i recommend the felpro 1 piece gaskets, they are awesome.

also before you go dropping the sump, check that the dipstick tube is fully seated.

edit: i say C*** of a job but in hindsight it's really not THAT bad, there are alot worse.
i think doing a tyre rotation is a C*** of a job too...

Tyres s**t me too. Still havent been game to look yet but if I can do the sump gasket without dropping the K-frame I'm game or stupid enough to try, hope its not the rear main seal. Thanks for the help.

Make sure it's not a PCV problem. I had the same symptom - oil coming out at the back after giving it some noise. Turns out it was a lack of PCV which allowed crankcase pressure to build and it forced oil out (the dipstick hole from memory). The PCV bit that gets blocked is the cylindrical wire filter under the black grommet. Hook it out with a bent wire under one of the tabs. Clean it in carb cleaner (or methylene chloride is even better), or just replace it.

Worth checking before you do a difficult job.

I looked under the car today and it's the sump gasket for sure.