So I've searched and I'm sure the answer is out there but I can't find it.

 

I have a 1990 Legacy with an open 4.11 differential.

 

Today I picked up a LSD from a 2001 5 speed RS. I believe that makes this rear end a 4.11 VLSD. It has male axle stubs, so I picked those up too.

 

 

• I've read that the VLSD does not need any additive to the rear gear oil. it this correct?
   
  
• Will these RS rear axles bolt into my Legacy?
   
  
• What should I know before swapping in this differential and axles?
  

I can say that the Viscous unit is sealed and contains it's own silicone fluid to make it work. Just fill with plain gear oil to keep the ring and pinion gears and bearings lubricated.

thanks guys, so should the RS lsd and axles bolt in to my legacy?

I would have figured you guys would know this answer to this. I guess I'll try the swap and let you guys know.

I really don't know which axles will fit what. I know there are some that stick into the diff, others have stubs in the diff that the axle slides onto, but I don't know which years or cars had which setup. I do know that you can not swap stubs from one type to the other because of differences inside the diffs. So you have to get axles that fit the diff, or at least the inner cups. 93-04/05ish? Impreza axles SHOULD be the same as 2nd gen Legacy (95-99) axles, or at least have the same spline on the hub end.

I really don't know which axles will fit what. I know there are some that stick into the diff, others have stubs in the diff that the axle slides onto, but I don't know which years or cars had which setup. I do know that you can not swap stubs from one type to the other because of differences inside the diffs. So you have to get axles that fit the diff, or at least the inner cups. 93-04/05ish? Impreza axles SHOULD be the same as 2nd gen Legacy (95-99) axles, or at least have the same spline on the hub end.

 

I have the axles that match the rearend. I guess the question is about hub spline and axle length.