You should have the 157 tooth, but depending on the bell housing that is on your C4 it could be 164. Have seen where a previous owner has switched trannys and also changed the flex plate to match. Usually the 157 had a 10 1/2 bolt pattern and the 164 had 11 and something but could be 11 on the 157 too depending on the converter used etc. Must use a flex plate that is balanced to the late model 5.0 engine(83 on up if I remember right 50oz) unless you put a early crank in a late block then you have to use the 28oz external balanced flex and front damper. Brain is a little soggy today so if I am mistaken, one of the other fellows will correct me.