It is my understanding that the SRT comes with TB #113 141 01 25 (74mm).
The NA comes with TB #112 141 01 25 (68mm) . . . I think your trusted friend gave you the part number for the same 68mm throttle body that you already have!
This is the 68mm that is OEM on the NA Crossfire
This is the one you want (74mm OEM on the SRT6)
You will find this to be helpful
https://www.crossfireforum.org/forum...tml#post575210
Here is the least expensive source I found for the throttle body O-ring delivered right to your door . . .
http://www.ebay.com/itm/MERCEDES-BENZ-3059970345-GENUINE-OEM-ACTUATOR-SEAL-/321627850768?pt=Motors_Car_Truck_Parts_Accessories&hash=item4ae2838810&vxp=mtr
Good Luck . . .