Yo! Greg!

[kowe69]

Greg, you recommended doing a 231/dana 300 doubler vs. the 203/205 to me a while back. I've been thinking about this and done a little research and it looks more and more like better option. I have a couple questions though. Anyone else who can offer any info please do. Thanks.

I found a kit by mad rooster but do you know of any other companies that offer adapters for this combo?

What about shifters?

Will a 231 bolt to a th350? Or is the output shaft too short?

Does my S10 jimmy have the 231 in it? I'm having a little trouble finding some application info.

What about a 203/dana 300 combo? are there adapters for this?

 

[Tacoma]

What's better about it?

It's lighter, but these aren't F1 cars. They require at least a little bit of custom wonderment, if you use all GM stuff you just need the Doubler adapter.

Tomayto, tomahto. Either way, you get lower gearing, and more options, yee ha

 

[Kiel]

I think Northwest Fab makes one called the black box. Check on POR in tghe venders section there were at least a couple others

 

[Greg]

Yep, there's a couple vendors making the kits. All of them are on POR. It looks like they're all the same, but when I was looking into it I was going to go with the kit from D.D. Machine, here- http://www.pirate4x4.com/forum/showthread.php?t=451754

IMO the NP203/205 is overkill for a mid-size vehicle, like your S10 Blazer. Those big doublers are probably just fine in a full-size rig that is already going to be heavy. Personally I like the reduced size of the 231/Dana 300 doubler. The Dana 300 isn't bad stock, but there's plenty of aftermarket additions that make it stronger & better like 32 spline outputs, twin sticks, etc.

I was going to go that route because I really liked having 2 gear ranges in my Toyota. I ended up not running a doubler simply because I found a cheap, new Atlas. By the time I bought the doubler, built the Dana 300 with HD outputs and a twin stick, and did the work involved for the doubler, I was close to buying a StaK or Atlas. I decided to spend a few hundred more & go for the Atlas. When you're ready, make sure you add up the cost of building the Doubler & compare it with other options. You may be surprised.

BTW... your Jimmy should have had a NP231 T-case. There ought to be a small round, red tag on the back of the T-Case that should have the model number on it. The doublers come with the parts to shift the 231 reduction unit, I believe. I don't know about the 231 bolting to the TH350, you'll have to research that one out.

 

[kowe69]

Cool, thanks a ton for the info Greg! You have been very helpful. I have just decided to leave the stock 4L60E in the Jimmy. This will save me some time and money. I had a chance to look at the t-case that was bolted to it today and it is a NP 233. I assume this is just an electric shift version of the 231? Doesn't matter though. My buddy has a 231 for me if I need it. I just have to get my hands on a 300.

And yes, I know doublers can be expensive. But if I go the 231/300 route I will likely just start with the 300, then maybe at some point install a 4-1 kit. Later if I still want the doubler I can add it. Building as I go will help spread the cost out a little.

 

[kowe69]

What's better about it?

Gearing options, cost.