I can tell you some things to check.
But keep in mind, things can get swapped/changed around.
And these are "box-stock" equipments i'm referring to.
If it has MPH as primary measurement on speedo - it is ECO.
No TD offered in USA after 87. But Eco was offered in USA in 91 and 92.
Canada got TD all the way through mk2 run.
If it has Kilometer as primary measurement - its Canadian, and Canada never sold the Eco. So it would be TD.
But either way - the speedo could have been swapped by now, so anyway.
The Eco came with a catalytic convertor, and either underhood or in driver door jamb (or both) it will say catalyst equipped on a decal. TD will not have that. It may even say Non-Catalyst on a TD if it has a decal.
An Eco will not have an LDA fuel enrichment aneroid on the top of Injection Pump. TD will have this aneroid. It looks like a small flying saucer from the 1950's era.
Usually on the radiator support there is a tuning sticker and it will say it conforms to USA standards - or Canada standards. That would be a good clue.
All these things could be added or deleted by previous owners as parts get swapped or repairs made.
There are other items too, but not as easily checked.
The block code really is the final verdict, along with the transmission code.
Both these codes are STAMPED, not cast.
As Rabbit stated, the block code is stamped into the block, front side, just below the head mating area, on a machined flat tab, between #3 and #4 cylinders. The water outlet flange, hoses and injector lines make it really fun to access.
1V is the Eco code.
MF is the TD code.
The block code are the first stamped characters to the left side of that tab. The following numbers on the tab are the engine unit number.
On the bottom of the bellhousing, the tranny code will be stamped.
AVX = Eco
The TD could have had a couple diffrnt codes in that timeframe - i think.
But the AVX code is Eco Only.