The later TF (along with the TD Mark2) used dual air filters, one on each Carb. (The carbs were also larger, 1-1/2" throat vs the 1-1/4" for the TD. )
This supposedly added a few HP.
Some TD owners have gone this way also.
Moss sells a "Look-a-Like" filter. Big bucks however.
https://mossmotors.com/air-filter-assembly-1-1-4-su-k-n
Gas Warning Light.
On the center dash panel are two lamps. One is fenerator warning the other is Low gas warning.
As to color and position, over the years these are often mixed up.
Making sure you have qt least 1/3 of a tank of gas, turn the ignition key on. Don't try to start One of the lamps should light. This would be the generator warning lamp.
The other should warn of low gas.
If neither light you have at least one burnt out bulb.
Often, after sitting, the low gas lamp wont work.
The sensor, in the lower rear of the gas tank, can be removed and generally fixed.