regearing

[46/72 truck guy]

Hey folks, Im a new member but long time truck lover. I just recently bought a 1972 K20 Cheyenne super with a 4 speed manual and 4:10 rear. I would like to change the rear gears to a more highway friendly set. Does anyone have a suggestion as to what gearing I should go with? ie 3:73 or 3:03 Any help would be greatly appreciated.

[Bigdav160]

A K20 would have came from the factory with a Eaton rear axle. 4.11:1 or 4.57:1 only

You will not find any aftermarket gears available.

A 14 bolt rear axle from a later model would be a popualr choice. If it were me, I'd look into a overdrive transmission (4L60) solution.

[Jahloha]

Originally Posted by 46/72 truck guy

Hey folks, Im a new member but long time truck lover. I just recently bought a 1972 K20 Cheyenne super with a 4 speed manual and 4:10 rear. I would like to change the rear gears to a more highway friendly set. Does anyone have a suggestion as to what gearing I should go with? ie 3:73 or 3:03 Any help would be greatly appreciated.

You can also consider running larger tires to balance out the low gear ratio. These rear ends are also known for being bullet proof, so that should be a consideration as well when looking into a rear end swap. But like Bigdav said, parts for these are becoming harder and harder to find.

[ole dollor]

first let me welcome you to the forum, I started out with a I line 292 six and a 4 speed with a 373 rear end, I change to a 276 gears and made a big difference on highway speed, but I think a 308 might have been a little better for all around driving, I never haul much weight, in you case it depends on the loads you are planning on hauling and what you plan to do with your truck.

[Prematuregrey]

At some point mine was swapped to the 14 bolt as bigdav suggested. Its got the 3.73's in it with a BBC/th400 and they are a good highway gear for it. Without a tach, I'd say I'm sub 2k RPM's cruising the highway at 70 with roughly 33-35" tires. That is what I'd recommend doing as long as your not planning any heavy hauling. Mine could use a little more umph when dragging my Toy (about 8,000lbs trailer and all) around on the steep hills but it gets the job done as well as any other truck I've hauled the same load with. I'm looking to switch it back to the 4.11's and then shooting for a winning lotto for a GV overdrive setup. I definitely wouldn't go any lower than 3.73's for a 4x4.

[Longhorn 70]

Welcome! Couldn't you also do an overdrive trans? Would it be too big a pain in a K?

[46/72 truck guy]

Thanks for all 00the responses. I don't plan on hauling any loads over 5000 pounds. I do have a set of 33" tires to try to start with. Id like to keep the manual trans and ill look into a 14 bolt rear. Again thanks for the great ideas. Now i know where to start.