I knew they would pull that. I took it to Jiffy Lube for the Dynamometer emmissions test required in my county. The car kept trying to climb out of the Dyno. I pressed what I thought was the traction control button and a little red light lit up on the switch , so I assumed that that would turn it off. Anyway, I left Jiffy Lube and went to Mercedes...(talk about lowering your standards)LOL. They did a state inspection . Cool ! Oddly enough on my reciept it shows all the correct info for my vehicle untill I get to the state inspection part where it says "State Inspection 96' NON DYNO OBDII Inspection ." LOL! thats one way to get around it. Now , If I can just find that OBDII connector ....

I'm not entirely sure where you are located, but I'm assuming it's the US.

Federal law requires that all vehicles sold in 96 or newer, must have a 'generic' OBD hook-up less than 3 feet from the driver's seat. Even though your SL is a 94, I'll be it has the generic plug. It's usually under the driver's side dash.

But Mercedes has a specific access port under the hood of all their cars. It's round, and has a black plastic screw cap.

Here is a pic of the electrical components under my hood. The CAN/Bus access is in the lower left corner of the pic, just above the '5'.

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)