Hold on there BubbaLoey
I have a feeling that the slug just represents the spacer in the TruTrac, making it a tool to determine any axle length adjustment(cutting) that may be required to fit it.Afterwards the slug is worthless to you.
Now shine a lite down into the center of your new TruTrac. If your new trutrac has a spacer in the center, then the the slug is just used beforehand as a set up tool to verify that the axle end-play will remain adjustable after the install.
If there is nothing in there, and you are using tapered timkin wheel bearings,then you must install that slug as a spacer in the new TruTrac.If you do not install it you will be unable to adjust the axle endplay, the axles will slide down the tapered races and the brakedrum will jam up on the brake shoes.
If you are running the green,ballbearings, then, after the measuring and adjusting,the slug serves no more purpose and may in fact prevent the bearing retainer plates from seating; so leave it out.
