J30 diff question

[SketchyRollin564]

so i always thought it was a simple switch for the s14 if its a 6 bolt, other than the driveshaft which is optional if you dont mind replacing the transmission rear main seal often

but sombody on nico brought to my attention after i posted a picture:

that i would need new bolts and bushings to mount this...

then i also read somewhere else that its only for the s13 that you need the bushings because the s14 bolts are long enough

so... what about the bushings? why cant i use the oem bushings? and where can i find new ones for cheap

[SketchyRollin564]

bump?