So I have a 1986 Bronco with a 302 4 wheel drive and granny 4 trans. I was trying to figure out what y’all think would be the best option for either replacing my trans or regearing it in order to get better highway speeds and gas mileage.

 

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You can’t really re-gear the just the rear, without affecting or creating a mismatched front/back ratio issue. You could size up on the overall tires/rims, or another option would be a Gear Vendor high/low 2 speed splitter. But normally, the cost to make changes normally out weighs the cost of lower ratio fuel burn demands and costs. My 0.02...