The OP appears to be in Egypt so might not have access to the same ATF brands we have in the US. Use whichever brand says it meets or exceeds Dexron II/III specifications. Synthetic fluid may have an advantage.
The filter I installed is aftermarket (one brand Magnefine) but it is not required and maybe in your situation better to not mess with it. Some people feel it's
not needed and could even add a failure point if it clogs up.
Doing a complete fluid exchange would be one option to change out all the fluid at the same time, but doing a few drain and refills of the pan might be safer (for the transmission).
We should've asked you this before, but what year/model 80 series do you have and which transmission? Look at the vehicle Data plate/sticker if you aren't sure. ?A442F
The gasket for the drain plug is different depending on which model transmission your 80 has.
ps: looking at the photo you posted, looks like a lot of hacks done in the engine bay; water heater hoses removed (not needed in Egypt), main engine harness not routed correctly, ----.
The filter I installed is aftermarket (one brand Magnefine) but it is not required and maybe in your situation better to not mess with it. Some people feel it's
not needed and could even add a failure point if it clogs up.
Doing a complete fluid exchange would be one option to change out all the fluid at the same time, but doing a few drain and refills of the pan might be safer (for the transmission).
We should've asked you this before, but what year/model 80 series do you have and which transmission? Look at the vehicle Data plate/sticker if you aren't sure. ?A442F
The gasket for the drain plug is different depending on which model transmission your 80 has.
ps: looking at the photo you posted, looks like a lot of hacks done in the engine bay; water heater hoses removed (not needed in Egypt), main engine harness not routed correctly, ----.