Any 87 Monte Carlo frame will work as it's the same thing.
in one word,no there not. they fall into groups,64 and 65 are the same.66 and67 are like each other but different from 64-5.then you have 68-72.
No, the 73 - 91 Suburbans are the boxy ones with 81 - 91 getting a little different nose treatment (sloped hood), but 92 on is completely different.
the ecu is located behind the kick panel on the drivers side under the dash. you have to unbolt the harness from under the hood. should be a 10mm bolt.
in 1987 it was a navistar.