converting to 8 3/4, support plate?

I'm new and dumb but have to ask. In my '65 GT I am changing from the 7 1/4 to an A body 8 3/4 with a 489 third member. In the '65 Dart/Coronet tech. service manual it shows on pages 3-2 and 3-3 the two axles in full assembly drawings and I noticed the lighter 7 1/4 case doesn't have a support where the yoke meets the driveshaft whereas the heavier 489 nose out to the yoke shows a large support plate that must bolt up into the undercarriage? I'm having a suregrip installed right now and my 489 case didn't come with that support plate. What is commomly done when hanging the larger 8 3/4 to support the weight of that big case? Can the spring perches alone keep it happy?