ATF + 4 became factory fill for all corporate transmissions including the 48RE, starting in the late 90’s.

There is no arguement that ATF solved much of our issues in electronically shifted and electronically modulated transmissions as well as hydraulic units like the 48.

We regularly saw 48’s with overs 200k miles and the clutches were still useable.
And that is seeing torque ratings higher than 95 % of anyone here is making.

In a 3 speed trans street or strip you won’t see any issues.