67 K20 Final Drive Ratio...

[martindc1]

Sometime in the past there was a bit of a problem with my 67 K20 (250/sm420). There was some kind of failure in the rearend and the seal surface got fouled up. Whoever fixed it used a repair sleeve. They did a pretty good job but there is a constant leak on one side that makes a mess and seems to be getting worse. So today I picked up another HO52, the plan being to switch housings. I'm pretty pleased as I got the axle and an original step bumper in good shape for 100 bucks.

So anyways, the new axle has a 4.11 and the existing ratio is a 4.57. So now I have this idea rolling around in my head to maybe go to the 4.11 ratio. Should I do it? The truck is mostly my camping and hunting rig, so it sees the road a good bit. Maybe some day I will pull a not-very-big camper with it. Tires are 265/75/16s, so say 32 inches and I will never go bigger.

I compared engine RPMs at various road speeds using a gear ratio calculator on the web, and I would save a couple hundred RPMs depending on speed. I suppose this would add up over time.

On the other hand I would have to change the front ratio to match. I have set up a few gear sets before and have the tools, so I'm not worried about that. However, there seems to be several applications of the D44 through the years so I am slightly concerned about finding the right parts. Although I may be able to sniff around on the boards for a used gearset, as a quick search revealed that many think the grass is greener on the other side. What kind of interchangeability is there between front Dana 44s through the years? Since mine is a closed knuckle. How common were the 4.10 ratios in the Dana 44 equipped trucks?

I reckon I could test drive the truck with the 4.11 third member when I switch housings to see if it would be worth it, then switch back to the 4.57 third member if need be.

Also, this new axle came out of a coil spring truck, so I'm assuming things are the same other than the spring perches correct?