I am basically familiar with the history of these engines on the 76 - 78 (?) Cessna's and the post T serial number designation for the modifications.

But my main question is with the non T engines from Lycoming that are modified later yet do not carry the T serial number.

Thoughts on these engines with the field modifications?

I am under the impression that if the engine is modified with the spray nozzles that the data plate is supposed to have a "T" added to it. Along with an appropriate log book entry.

The "T" mod uses larger diameter tappets. A field modified engine is essentially the same as a factory "T". The oil squirts are not part of the "T" configuration/ That is a Chuck Ney STC. Charlie Melot Zephyr Engines

So do the field modified engines get a new data plate with the T?