Author Topic: 84 k10 Silverado axle and gear swap.  (Read 876 times)

Offline Sheriff_of_Rock_Ridge

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84 k10 Silverado axle and gear swap.
« on: August 20, 2018, 08:33:20 AM »
The truck is a 305/700r4/3.08 1984 short bed.

Itís getting a new 350 motor and I would like to swap out the axles. 

By suggestion from some people on this site I would like to ďwake upĒ the truck with a 3.73 rear end.  Itís a daily driver for a construction job that needs Offroad capabilities.  The gentleman was saying with the overdrive that the 3.73 would still be a good gear on the highway. 

My questions are
 1) if Iím going to scout the junk yard or Craigslist what should I look for? For example there is a 2002 Tahoe with the 3.73 that I can pull myself for $200.  Should I only go after something from 73-86?  Does it have to come off a Chevy?

2). Do I just need to re gear the front?  The front gears have to match the rear correct?

3.). Can i re gear the rear I have?  I assume it would be cheaper to find a used one.

Thank you for the help. 

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Offline Irish_Alley

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Re: 84 k10 Silverado axle and gear swap.
« Reply #1 on: August 21, 2018, 08:13:21 AM »
my opinion of this is upgrade front and rear at the same time out of a k20 in the 73-91 family if you really want to beef it up go for a k30 (dana 60 upfront but it can cost you some cash). try and find a 14 bolt full floater for the rear. the front wont matter as long as its a matching rear. also if you plan on hauling anything heavy i would even op for 4.10 ratio. and if you find a 14 bolt full floater it will prob have the 4.10 ratio. if you didnt have OD i wouldnt suggest 4.10.

if you want to try and regear your front have at it but screw ups can be expensive and to pay someone to do it for you can also be expensive.
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Offline 75gmck25

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Re: 84 k10 Silverado axle and gear swap.
« Reply #2 on: August 21, 2018, 08:48:25 AM »
You want to get a full set of axles from a square body, not a newer truck.  If you can get it from one with the same transfer case I would also pull both driveshafts, because the ends are sometimes different from year to year.

4.10 was a common gearing for older 3/4 ton trucks, and it was often used with the 14 bolt FF.  I have that setup on my K25 with a TH350, and its a little busy on the highway, but with a 700R4 it should be fine.  A 14 bolt FF rear and Dana 44 HD front are a very stout combination.  If you already have 16" tires, you can usually buy used 8 bolt 16" steel wheels for about $25 each, and just have the tires moved over.

3.73 gears were also fairly common on 1/2 tons, but some (like yours) had much higher gearing.