Dana 21 replacement

[Rockcrusher]

I've got an NP435/Dana 21 in my '69 and I want to swap in EB Dana 20. Are there any major issues involved.

[willowbilly3]

What is the EB 20 and what was it's parent vehicle?

[Rockcrusher]

What is the EB 20 and what was it's parent vehicle?

Driver side drop Dana 20 transfer case from an early (66 to 77) Bronco. They had either a 2.46:1 or 2.32:1 low range.

[willowbilly3]

I don't know if there is an adapter to use the Bronco T-case on the big NP tranny. I can get you a 205 which is about the best one you can get. I don't know the condition as it is in a junker. Also not sure how expensive shipping would be.

[Rockcrusher]

That's why I was asking if there were major differences between the stock 21 and the EB 20. I would just as soon use the 20 I already have 'cause it's got a better low range and is considerably lighter than a 205.

[willowbilly3]

Tell me about the low range. Better as in a lower ratio? I had a 75 Bronco Explorer but never used low range I don't think. I wish I had that one now, except for those horrible brakes. I would have to put it in park at red lights because my leg would get a cramp holding it in drive.

[Rockcrusher]

The NP205 has a 1.96:1 low range and my Ford Dana 20 is 2.46:1. That translates to a low gear-low case ratio of 46.4:1 for the NP205 and 58.3:1 for the Dana 20. With hard gears, lower is better. Since I don't do any hardcore wheeling with the truck, the 58:1 ratio will be OK. I would set up a dedicated trail rig with hard gears for at least 100:1 low gear-low case.

I would bet that you had an auto trans in your 75 and that creates a special set of circumstances, the most important being the torque multiplication of the transmission. To compensate you have to do major upgrade to your brakes or you'll drive thru them.