The top hat spaceer is a piece that he made on a lathe. Its a bearing adaptor that looks like a small hat. The Nissan bearing inner diameter is different from the stock Chevy so he needed a adaptor to match them up. The Hard Body Nissan was a truck model from '86 -'97 ( http://en.wikipedia.org/wiki/Nissan_Hardbody_Truck ). Jim also hand made the caliper brackets.

Joe