There were some early P38's that didn't have TC at all,
2 Wheel TC on the rear wheels was pretty standard, and then 4 wheel TC from '99 onwards.
As Gilbertd says, you can swap bits over, but I think that it's more than the ECU and modulator - you would also need to redo the wiring loom, as the connectors between the earlier/later ECU's are different, and there are more wires to the modulator block aswell from memory. Not a simple plug and play replacement sadly, but not impossible
'06 4.2 Supercharged Black/Cream "Jess" -- Bought April 2021 (NZ)
'01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
'99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
'95 4.6 HSE Epsom Green/Tan -- Traded June 2008