The differential is a system of gears that allows different drive wheels on the same axle to rotate at different speeds, for example when your 1978 GMC G25 is turning. Your outer wheel travels a longer distance on a wide turning radius, therefor it needs to rotate faster. Without a differential the outer wheel would slip making your 1978 GMC G25 much harder to handle and wear your tires out at a dramatic rate.

When browsing for a differential there are different terminology you will run across and its important to understand what each one is. Front-wheel-drive (FWD) the differential is alongside the transmission inside a housing, and the unit is called a transaxle. Rear-wheel-drive (RWD) vehicles the differential is between the rear wheels and connected to the transmission by a driveshaft. All-wheel-drive (AWD) and four-wheel-drive (4WD) vehicles add a centre differential or a transfer case to distribute power front and rear.

The simplest and most common differential is the "open differential". It gained its name because the wheels can always turn independently of each other. Its main drawback is that if one wheel doesn’t have traction, such as if it hits ice, it still gets lots of power. It spins helplessly, and you go nowhere. To combat this situation, some manufacturers use electronic systems that detect spinning wheels without traction and send signals to partially engage brakes on that wheel to channel the engine’s power to the other wheel on solid ground. A hydraulic differential lock can be temporarily engaged in a difficult off-road situation when one of the drive wheels digs deeper into snow, mud, or sand.

If you are an enthusiast looking for better vehicle handling for cornering, faster acceleration on the street, strip or track then you may benefit from installing a high-performance ring and pinion set with different gear ratio’s. Browse our digital shelves for your 1978 GMC G25 to find a huge assortment of premium racing differentials and related components, such as durable and lightweight differential cases, housings, rings and pinions, spider gears, and much more.

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Arb Usa RD114
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Arb Usa RD114 Differential
for 1978 GMC G25 ALL

$1,415.65

Save: $184.65
Sale Price:

$1,231.00

Estimated Ship Date: Today

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In Stock - 2 New In Stock
EngineFit NotesFitment Notes
1978 GMC G25 ALL equipped with
L
 
Axle: GM Full float 14B 10.5"
Shaft: 1.56"
Spline: 30
Ratio: All
4.56 and up ratios must use a 'thick' gear, confirm axle is 14B full float
 
1978 GMC G25 ALL equipped with
L Axle: GM Full float 14B 10.5"
Shaft: 1.56"
Spline: 30
Ratio: All
4.56 and up ratios must use a 'thick' gear, confirm axle is 14B full float