Let me see if I am understanding this right. Two bolts connect the speed control pedal to a piece that's fixed to the tractor's frame. As you rock the speed control pedal, the part attached to the frame rocks with it. There is a long silver rod that's bent at each end (its 130 in the picture from your dealer) piece , and it connects the speed control pedal to the piece controlling the actual speed - which is by the hand levers. The long silver piece is just connected with clips that look like bent paper clips at one end, but it's threaded at the other.
This linkage runs along the inside of the frame, and you could probably access without removing anything if the connection under the speed pedal is unhooked. If you remove the step (which is a pain) and the fender (which is easy once the step is removed) you can very easily access all of the linkages. I did this with the step removed, and, again, it was very easy and pretty straight forward.
linkages run from the bottom of the piece attached to the frame along the inside of the frame rail to connect to