There is a small tool available to remove and replace them without disassembling the trans. You just have to pull the driveshaft. I think I paid $135 for mine. It comes with adapers to do GM & Ford bushings too.
The real issue for these bushings and driveshaft yokes is that the clearance on the replacement parts is excessive resulting in too much movement of the yoke once installed. I put a fresh bushing in my transmission and the new yoke still had excessive play once everything was assembled.
A machinist buddy of mine traced a high speed vbration to these components, machined a tighter fitting bushing and his nagging vibration was finally cured.
My A-Body has a high speed vibration that is dead smooth until about 95 mph, and then it starts to vibrate at an ever increasing rate as the speed is increased. By 130 mph it is down right scary how much it vibrates.
