Look for the metal manufacturer tags. Usually under the hood an/or on the inside door frame. Pics posted here would greatly aid us in identifying their ages.
You can also find the frame number stamped on the passenger side of the frame rail near the front. Then check in at SOR's site (at least for the FJ45) where they are listed by year. Go to this link and scroll down the page to the bottom: Specter Off-Road-Land Cruiser Parts - Vehicle-Identification
I've always thought a BJ41 was "Japanese Domestic Market Only" with the timeframe fitting between the exported BJ40 and BJ42 models which would make it a 1980/81 model. (But as always - I could be wrong.)
Hiluxonian posted some pictures on an earlier thread, troopie is later than 1969! VIN on the FJ45 is FJ45-307962.
I have papers for an FJ45 registerd in the UK in 1977 and the VIN is Frame/Vin FJ45/106641 so quite a bit later than that, probably get a good check with the FJ45 registry?