Mounting Bennett shifter

[Iver]

The instruction manual mentions some nylon bushings where the bolts go through the mounting holes to attach the bracket to the transmission. (allison 754)
The existing bracket holding the cable shifter doesn't have the bushings.   I don't have them.  Are they necessary?

Also there is a steel ground cable on the back of the bracket which I imagine bolts to the trans.?  Maybe the bushings would insulate the bracket from the transmission so a ground strap is needed??
   Any thoughts,  thanks, Iver.