I will offer this....these motors come in families. It is often not necessary to ID the motor down to it's exact year. For example, the same piston is used in V4, V6 crossflows over many, many years.
So, if you can ID the family by comparing, looking at parts lists, etc, you can probably find all your parts without ever knowing the exact yesr.
The V4 crossflows were made in 90, 115, and 140 hp over many years. They all use the same piston.
The V6 crossflows were made in 150, 185, 235...(probably many more models) over many years. Same piston, and even the same piston as the V4s.
All with 3.5 inch bores.
Loopers the same way. The V4 looper uses the same throttle plate assy as the UPPER cyls on the V6 looper....same pistons, rods, bearings on the V4 and V6 models...3.685 in bores.
This is not always true, there are year differences, but it is very often the case that you can get your parts by just looking for the engine "family".
This may not sit well with some of the purists on here, but it is a practical fact to know, and it makes these engines a little less mysterious.
I am researching right now...the diff between a 1985 V6 crossflow crank and the 1987 V6 crossflow crank. They are different part numbers, but I would bet that they are the same part functionally, and will interchange. NOT SURE, but that is my feel right now.
Go to some of the aftermarket sites like Sierra and PromarineUSA.com and just start looking at the application parts pages. You will see what I mean.
