Hello. First post. I have a Manfrotto 400 Geared head coming my way and have been trying to find the diameter of the top of the quick release plates but have found differing numbers. I found 2.95" twice and was hoping someone with a plate could give me its dimensions. I want to mill a conical shaped adapter going from the top of the quick release plate to a 1.5" diameter threaded adapter that screws into the bottom of my 19 lb. searchlight. Any help will be appreciated, especially dimensions taken with a caliper if possible.