8 3/4 posi unit change

I looked at my axle housing there isn't any adjustments on the right side on the housing just the metal seal but what I need to find out is if I put this posi track in it do I need to put the plates back on the rearend axle housing
Yes the plates go on. That’s what holds the axles in. If you don’t want your axle sliding out on a curve and waltzing across the road, put them on.

Two, again, no posi-track will fit a Chrysler 8.75.