1990 Dodge Ram 5.9 CTD: I'm considering changing to a newer automatic transmission so I can have a lockup torque converter. Will I have to also change the ECM? Does the ECM control the lock-up converter or is it controlled entirely by the transmission?

 

I think most people just put a "mystery switch" in to engage lockup.

 

Does that mean that a lockup style torque converter could be installed into an older transmission, with the addition of a mystery switch?

 

Its alittle more complicated than that, I'm not even sure it worth trying to do to a 727 trans.
Its easier and probably more cost and time effective in the long run to swap the whole unit in. A 47RH out of a 94 or 95 truck will work.

I'm off to bed now, but I'll dig up some more details about doing a swap in the morning.