You can upgrade the original slipper and top shaft from the rc10 DS,B/T 1,2,3,4 to available modern parts.
AVIDRC has most of the parts needed.
Avid making the b4 top shaft without the built in spacer, allowing it to work with the stealth in all imperial bearing gear boxes b/t1,2,3,4

The slipper,pads,gear and springs can replaced with a Triad slipper kit.
Note that there was a change in the way the slipper worked after the original b6/t6
the slipper replacement kit is

Replace the top shaft and install the slipper kit.
I have this setup on one of my running cars and it does require that you make some kind of spacer to go between the transmission casing and the back of the slipper plate, otherwise you get spur gear rubbing on the motor mount.
That upgrade has a much longer than stock top shaft and requires a new gear cover to fit over the top shaft.
The proper sized gear cover is currently only being made for the original RC10/b/t/ds

RPM RC10 Classic Gear Cover RPM70081
If you upgrade the slipper on a b/t2,3 I am not aware of a proper gear cover that is being made.