SEAL?,etc
 

Question,1 Should the seal between the fuel shut off valve, and IP be replaced when replacing the(sov)? Is it available?
A new seal wasn't included with the metal type (sov)

When I replaced my SOV I didn't. Seal was in good shape. I'm trying to remember if it came with one, but I don't remember. I installed it wrong the first time, but didn't have a runaway, it just took longer to shut down. I did have to reseat it in the groove. I went below it. No power, slow shut down. You may want to replace the o-ring that comes out the side that the manual shut off valve connects to.
Here are a couple links (good info):
http://www.peachparts.com/Wikka/OM602ShutOffValve
this links to original post above and member comments of doing this
http://www.peachparts.com/shopforum/diesel-discussion/190780-shut-off-valve-replacement-w124-602-3-300d-2-5-a.html

Good Luck. It's easy, just pay attention to the details.

Where can I get the o-ring for the side stop lever?
Thanks for tips.

It's just a metric O-ring. The o-ring is about 12mm across (outside diameter) and about 2mm thick. The inside diameter is 8mm. You can get a kit with different sizes for a few bucks.
Here's the link with instructions:
http://www.peachparts.com/Wikka/OM601InjPumpOilLeak

Thanks again for the info, awesome website for Mercedes owners.Wow!