So, I'v been thinking which way to go for a build i'm planning on next year. A 203/205 doubler or a dana 20 with terra low kit. Wanted some input from the club. I know that the final ratio's are not comparable, but looking at the cost side, and would i even use the extreme ratio of the doubler. I have a D20 (T-shift) and a married 205, sitting in the garage awaiting a direction. I will be mating one of these to the C6 i have. So here is my delima.
D20-
smaller
Gear set will be ($850)
output shaft is weak (?)
will need to get a C6 adapter ($500)
twin stick kit

203/205 doubler-
will have to find a married Ford 203 ($200?)
doubler kit ($500)
triple stick kit

regardless, I will have to get drivelines so that is not part of the delima yet. I plan on building a buggy with 110" wb. Let me know your thoughts!

I would say doubler or atlas, I've installed the teralow kits in jeep Dana 20's and don't like them, you have to grind a lot out of the case, and it takes a lot to break a dana 20 output, I drove the piss out of mine including 4k launches in granny low and wheel stands and speed shifting the np435 for 5 years daily before I broke mine, and Wildhorses sells upgraded output shafts. But I think for the money just buying an atlas 4speed is the way to go

I've been thinking about the same question. It'll likely come down to what kind of wheeling you're doing (hardcore, I'm assuming, since you're building a buggy). How much engine are you stuffing into it, and how heavy are you on the skinny pedal? I'm likely to go down the road of the built D20, as the output shaft issues can be addressed. I'm not planning big power, I'm a slow and careful type of wheeler, and I don't do huge trails. The other consideration is weight and size. The doubler setup is much stronger than a D20, but is more complicated and weighs a ton. A D20 weighs somewhere around 75 pounds, while a 205 is about 140. Figure another 100+lbs (a 203 weighs 165 lbs) for the doubler adapter and 203 and you're hauling at least another 150lbs over the rocks. It's down low, but it's still there. All that mass takes up room as well, so you'd have to account for that.

If you're pushing big tires and big power go for the doubler, otherwise I'd stick with the D20. You've considered an Atlas or Stak, right? It isn't _that_ much more expensive, and since it's a buggy you don't have all the issues you would normally have with getting one into Bronco.

Thanks for the input. Yes... I have thought of a Atlas. I plan on a mildly built engine (probably in the 350-400 hp range). Your right, the doubler pieces are HEAVY. I have never broke a output shaft in any of my EB's, so I dont know why I worried about it now. I'm more of a catious wheeler versus a hammer it! I currently have a set of 38.5's, but plan on running 42's. Thanks again, feel free to pipe in on any additional pro's/ con's that may come up.

One other thing to possibly look into is a black box i from northwest Fab. Takes place of the adaptor and is a planetary gear set. Its either 1:1 or 2.72:1. I'm planning to run one with the Dana 20.

Whatever you decide, go as low as you can. You won't be sorry. It takes stress off your tranny, which is extremely important with an Auto. You're looking in the right place to do it too (T-case). The control you gain by going slow is astronomical. With an Auto tranny, you don't need extremely low, but 5-6:1 in the t-case would be great.

I looked at all the offerings a few years ago and have never been sorry I went with an Atlas 4spd. It gives you the low gears, but has the flexibility to give you other options. You can do better price-wise than on Advance adapters. Let me know if you'd like my contact. I wanted the 10:1 low and nothing else offered that. And I do use the low-low a lot!

J.D.

A lot of good info to comptimate. Thanks all for the insight

203/205 is a lot of weight hanging off the back of a C-6 aluminum case. If you decide to go that way, make sure you put another mount at the back to keep the parts from bouncing around. It's also a lot of drag and moving parts.

On the Tera-low, I don't think there's any grinding on the EB case; however, the amount of preload is critical to get set up correctly. I believe you can get the Tera-low set for a lot less than $850. You can also get the C-6/D20 adapter for $300ish, give me a call if you decide to go that way.

Having run both setups, as well as an Atlas 4-speed, I'd recommend going with the Atlas if you can afford it ($3Kish delivered last I looked). Two years in a row I broke my D20 on the waterfall of Upper Hellderado in Moab. 1st time it stripped 6 teeth off the low side of the intermediate gear, 2nd time did that as well as breaking the case into 4 pieces. I never have broken the output shaft......
HTH, Joe

Where can you get tera-low gears for cheap? I'm planning to go that way when I rebuild my t-case. I doubt I'll ever do anything like Helldorado.

Try 4X4 Group Buy.

http://www.4x4groupbuy.com/store/index.php

It was about $780 a few months ago. Delivered.