No one knows? How fast have you guys gone before replacing axles,yokes, driveshaft,rear cover, c clips,or bracing
the lower control arms?
in order you asked
axles- id replace if launching on stickies or 10s , nhra says you need to do it
yokes - should be ok unless you t brake launch but ill gaurantee you'll twist the splines in the stock trans yoke long before you reach 10s
driveshaft- i'd do it for 10s but many have done with stock shaft and got lucky . at least do spicer ujoints, if doing the shaft upgrade to 1350 joints
rear cover , i didnt have one but its cheap insurance and looks cool
c-clips elims -NHRA says you need them for 10s , they are a pain , i'd do the ford ends instead
boxing lowers - id do this for a stock turbo car , cheap enough and do all the bushings with poly , also not a bad idea to reinforce the front frame mounts for the lowers (weld in the hrpartsnstuff kit)
oh and if its a stock trans , all bets are off once your faster than 12s, for 10s it needs a quality rebuild by a turbo buick trans builder with some good parts