90s F-Super Duty, if Pre-1999 anyway, was what's known as a F450 nowadays. Similar GVWRs, etc. F450s went 10 lug and 19.5s whereas F-Super Duty was 8 lug and still 16" wheels but otherwise, similar notions. Leaf sprung beam front axle, etc.
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Front leaf spring specs from 1994-1997 F-Super Duty and [1988-1993 F-Super Duty] and (1999-2004 F450, F550, 2wd and 4wd):
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Motorcraft # F4TZ5310AF4TA5310HA [E8TZ5310A and E8TA5310AA] (YC3Z5310AN and YC355310APC)
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Width: 3" [3"] (3")
Length from centerpin to front eye: 23-7/8" [23-7/8"] (27-1/2")(measured flush with top spring)
Length from centerpin to rear eye: 28-3/8" [28-3/8"] (28-1/8")(ditto)
Arch: 6-1/4" [6-1/4"] (4-7/8")
# of leaves: 2 [2] (2")
Total thickness:1-9/16" [1-9/16"] (1-5/16")
Spring capacity: 2,250 lbs [2,250lbs] (2,630lbs)