Is that a '75 F100 truck?
@Navigator
I had a '74 F250 4x4 with a Canadian 300CI straight 6 with forged crank and Holley 350. Got about 11 Mpg and that was our big 4.54 litre ones.

Though I did have a twin axle tipping trailer on it or a small Kubota tractor and slasher with it pretty often.
It had the Dana's front and rear and big
drum brakes all round




.
Mine had a horrible habit of losing all lights without warning for a few seconds before coming back on while driving home in the dark from my bush block! Freaked a few approaching vehicles out but never found the cause.
I had a '63 F350 Dually flatbed too I towed to a mate's place for parts but I'm sure it still sits there rotting on a 5 acre block South of Darwin with another '78 F100 I left there too..