i am converting my 46 mercury to tube shocks,i have mounted the upper front mount but did not drill the hole in the front axle yet. i checked the distance between top mount center and where i think the hole in the axle for the lower mount should be is 17". a stock monroe shock for this car only extendes 17.88".it will fit but is this extended length enough to let the car roll from side to side? what i am trying to find out if the distance is 17" center to center what should the extended length of the shock measure. same with rear center to center is 21". thank you all