is there a way to acess a fixed joint (or other types) trough its transform (i can only do it for a hinge joint)

i am trying to check if a fixed joint exists on the transform but for some reason in my if statement myvar.fixedjoint (or myvar.Fixedjoint)returns the error 'fixedJoint' is not a member of 'UnityEngine.Transform'

i have tried this with all joint types capitalised or not , only hinge joints work and checking if a transform with a fixed joint has a hinge joint returns false

this is my code as i need it but it doent work

i could use hinge joints instead of fixed and it works but am worried about efficiency and anyway im curious as to why this is

 var thisinfo : Transform; 

function Start(){ thisinfo = transform;}

function OnCollisionEnter(c : Collision) { if (thisinfo.fixedJoint == null) { var joint = gameObject.AddComponent(FixedJoint); joint.connectedBody = c.rigidbody; } }