Is there a difference between the ibeams from 1973-79 ? I have a 1975 f100 and a 1978 f150 .

F150, 1978

F100 , 1975

 

One thing that I know that changed in the ''73 I-beams is the pivot bushing size.

 

C5TZ-3B177-A .. Axle Pivot Bushing - 2 1/4" O.D. x 5/8" I.D.

1965/79 F100, 1975/79 F150.
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D2TZ-3006-C Right & D2TZ-3007-C Left .. I Beams

1971 F100 from serial number M00,001, 1972/74 F100.
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D8TZ-3006-A Right & D8TZ-3007-A Left .. I- Beams

1975/79 F100/150.

1975 was the first year that a front stabilizer bar was available for F100/150 2WD

The 1975/79 F100/150 2WD radius rods (D5TZ-3A360-A) are also different than 1965/74 F100 2WD (C5TZ-3A360-A).

 

Comparing I-beams and Spindles - FORDification.com Thought this was interesting.