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Discussion Starter · #1 ·
Is the overdrive in this trans actualy 31%? The tranny is out of '92 dodge diesel 4x4. I am considering using it in a conversion with 3.54 ratios in the rearends, but am concerned my gears will be to steep for the 4bt. Any info would sure help.

Thanks,
Dallas76
 

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How tall of a tire are you planning on using?
What your usage profile going to be - highway usage? daily driver? weekend warrior?

The 518 has a 2.45 first gear so you don't have to worry as much about spinning through first as quick as say a 700R4 (3.06 1st) or any of the manual transmissions (all above 5.00). Heck, almost all of the stick's 2nd gears are higher than the auto's 1st gears.
 

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Discussion Starter · #5 ·
My plan is to buy a dodge 4x4 diesel pickup (1990-1994), sell the 5.9 out of it minus the bellhousing and a few other components. Then use the tranny, transfercase, and front and rear ends under a 1967 ford f250. The rear ends are 3.54 with 255/85 16. With all that, I figure that at 1800 rpm I'll be going 71 mph in 4th gear but in 3rd at the same rpm I'll be at 49 mph. Every thing that I read on this site says that for optimal fuel economy I want to run at 1600-1800 rpm. Most of my driving will be maybe at an average of 60, that puts my rpms at 1517. Do you guys think that is to slow rpms?

dallas76
 

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With that 7,000 lbs truck I wouldn't go higher than 4.1 on gear ratio, which should be the stockers. You need the lower gears to get it up and going. Still allows a good cruising speed stock, or you can add a 3,200 governor spring. You'll get good mileage with those gears. Nice thing is you also save some considerable money on a gear swap.
 
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