Maybe a better question is how do I know if a given Blazer has the np233 in it? Where is the part number located on the case? Can I see it while installed in the vehicle?

 

Look on E Bay. Some sellers will tell what years they fit. (Hint it must fit the same year truck as your van) They only list for what they think you will use it for.

 

Look on the case

I got mine out of a 99 or 00 blazer.

 

Far as I could tell, all the S10/15 vehicles with the 3-button 4x4 used a 233 case....

Most listings on ebay show them as interchanging through all those years (approx 1995-2003), but I did once see a listing that showed more detailed interchange info and seemed to show some minor variations (I think this was on some rebuilder's website) ... I used a case from a 2000 Blazer and it bolted into my 04 Safari with no mods.... I also used the wiring and switch since I don't have the skillset to fab a manual shift....

 

Cool, thanks guys.

Gavio, do you have a thread showing how you did the wiring/switch? Is it a matter of just plugging stuff in?

 

Is it a matter of just plugging stuff in?

Fat chance

But funny you should ask. I've been planning to document exactly what I did on this forum soon...

Basically, you add the 4x4 TCCM, encoder, switch and wiring from a Blazer and bypass the existing AWD TCCM and wiring.... There is a thread on the other forum that shows how someone did it for a 94 Astro, but there are a number of differences for the later models....I was unable to find a thread online that specifically listed what to tap into on later model Astros ....Also there are minor differences between the TCCM wiring in the 95-97 blazers and the 98-03 models.... I've had one of each in mine, and the later one makes for a more seamless engagement of 4 lo......... Hopefully this weekend I can get my info up....

 

I sourced an np233 out of an 98 s10 with 84k on it. Now I just need to fab up some linkage and I'm good to go.

Can anyone explain or link me to how 4lo works on these? I have seen a few threads that show a separate switch needed? I am confuse.

 

The 233 just has 3 positions - 2Hi, 4HI, 4LO..... If you fab a mechanical linkage, you can shift between all of them.... If you leave the Astro front axle alone, you have working 4x4... If you want to have the front axle disengage, then you install the RH half of a Blazer front axle, and connect a cable to operate that, or use the stock Blazer system which uses a vacuum switch built into the t-case.... Only other thing is that the Blazer TCCM sends a signal to the PCM when 4LO is engaged which allows the tranny to shift at lower vehicle speeds - if you're using a mechanical linkage, then you need to send a signal to the PCM or else you'll only get first and second when in 4LO.... I don't recall whether the signal is 12v or ground off hand.....