Hi Dan,
I agree with Chuck it was a PITA.
I installed the restrictor plate while in the car as I forgot to put it in when I had the engine on the engine stand.
I used a socket with the same diameter as the plate and a hammer to tap it in place. If I remember correctly, I did this from inside the car.
Not sure how to remove the old plate unless you can get something sharp under an edge to pry it out.
John
#3590