Typically F-150/Bronco lift springs have a much higher rating than stock springs. Also, they are ~1.5x heavier than needed due to the TTB geometry.
Is the F350 4wd w/D60? If so, using ‘lighter’ TTB coils on it would be about what you need.
I did a coil & radius arm conversion on my truck years ago using Bronco coil towers and radius arms I built to bolt onto the original leaf spring seats on the D60. The axle side radius arm mounts have a bracket and bolt to use TTB lower spring retainers.
I used 05-08 F350 Rancho 2.5” lift springs that ended up having the same basic measurements and calculated specs as some 4” F150 TTB springs I had on hand.
So yeah, basically the F series TTB lift springs will most likely be just fine under an IDI. You’ll just have to fine tune it to get the lift you want.
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