Firstly, the Avante doesn't have a slipper, it's a centre differential and shouldn't slip. You can replace them with the same parts from the Avante rerelease and you can find the current part numbers in the rerelease manual.
If you want to fit the Egress parts they will drop straight in. You have the option of the sold drive or a one way torque splitter.
For permanent 4wd you need the 9335621 Egress gear parts bag and 2595062 Egress locking joint. For a front one way you need a few more small parts to put it together as well as the one way bearing and shaft.
Manuals for both the Avante and Egress rereleases are on Tamiyas website:
http://www.tamiya.com/japan/download...8489avante.pdf
http://www.tamiya.com/japan/download.../58583-144.pdf
You can find all the new part numbers in there.
Alternatively you can go for the 84257 Avante Torque Splitter set, which includes the Egress centre solid/one way and Egress front and rear ball diffs in one package to upgrade the whole transmission to Egress parts.