Where are you reading the engine numbers from on the trucks? Those don't look like engine numbers. I think they are the army parts catalogue number for the engines.
Engine numbers start with AGD and then will be 282 for the MK3 & 4's and 283 for the 6x6's, unless they have had an upgrade/swap.
The engine number is stamped on the metal ledge on the passenger's side of the engine, where the oil filter housing and oil cooler pipes join the block.
Pretty crappy picture. The round thing with the slot across it under that little pipe is the cover screw for the pressure bypass ball. It screws into the block that has the 2 oil hoses attached underneath that go to the oil cooler radiator.
Looking at the list in the REMLR library, your engine number on the MK3 should be AGD282.9918, unless it has been changed again. The original engine was AGD282.7407.
It was disposed of by the army on 22.09.1982.
That's a very early chassis number. Your ARN, Army Registration Number, was 107-109.
As a comparison, my MK3 is 170-952 with chassis number 771.
Now, as for your F1, are you really certain you are looking in the right place? The chassis number should start with 6X6.
You may need to clean the paint back with a wire wheel or similar.
If you can find the engine number, we can possibly work back from there.