Front and rear RS diff swaps

I can pick up a Evo 4 RS diff and a 4-9 front diff.

1st i want to make 100% sure they will drop into my housings.
2nd I want to make sure that I am not wasting money on something that is not really the best way forward.

I have a Non-ayc (plain open) diff on my 2001 factory manual.
So will the evo 4 RS diff swap over? (can only find a bunch of info on AYC diffs)....
The 4-9 front diff should swap over according to my research but confirmation could hurt.

2nd, is the 4 rear diff a good way forward or are there better options.
I can get the set for 1500 euro, where I also found a 8 RS diff where they asked 1500 for the diff alone.

Much appreciated!
Attachment 81822
Attachment 81821

I'd like to do this swap at some point too, I'm sure someone here knows what fits!

For a direct swap, the Evo 4-6 front helical diff is required. TME (6.5) and up uses a slightly bigger diameter diff, which will not fit into the VR-4 transfer case without fairly decent work. I can outline what you need to do, but its much easier to get a 4-6 helical LSD, upgrade the bolts and be done.

I believe the only real difference in the Evo rear LSD is that the diff cover is different on the VR-4. As such, you should be able to just swap that over and have a direct swap.
I think you can also add the Lancer Ralliart and Galant Fortis Ralliart to that list, as they seem to have the same rear diff internals.
That said, you can also just get the actual diff from a Evo3+ and have that installed in your existing housing. Any aftermarket LSD for Evo3+ will work too.

Keep in mind that the VR-4 rear diff cover has no cooling fins, so heat management might be required. Same with the transfer case, where you should probably go and do the 10mm bolt upgrade at least. A spool to remove the VC in the transfer case might be a good idea too, as that thing gets pretty hot. Having no VC is apparently a good idea if you just plan on being on tarmac. After reading up that when racing on tarmac teams would remove the VC, I tried it and found it to work very well.

Thanks Kenneth,

But with VC you mean Viscous Coupling right?
And its the viscous coupling from the center diff that's located inside the transfercase?

Yes, that is correct. Your first picture shows the VC and the front diff.
Its nice and easy since you can do everything without removing the gearbox.