2nd gen BW4472 to NP233

[chuck.z]

Hey there guys. I'm hoping to gather up enough information to feel comfortable about doing this swap in the future. I have a 1996 AWD and have cheap access to a 233 from a 97 blazer.

So here's my question: has anyone done this on the 2nd gen vans with the 4472? I've seen the stickied threads on the 1st gen report and late 2nd gens with the np136 (direct bolt on!!), but the situation may be a little different for the earlier models.

Looking for any info that yall may have came across regarding drive shafts, clocking, crossmembers, etc.

Thanks in advance!

[photo_van]

I'll take a stab at this. I don't know much about the 233's, but I'll assume that they are very similar to the 231's other than an electric switching motor. Sooo. They come in various lengths, clocking and output splines.

If you are lucky, the clocking will be like Lifted's most recent conversion and you won't have to modify the cross member, otherwise it will be like TLow's and many others that require a small modification OR shimming the rear mount up.

Secondly, there is the rear output spline count 27 or 32 and different lengths of rear output shaft/tail housings. Look at Lifted's original conversion on the SPB (98 Astro). The rear driveshaft was a direct fit (right length and 27 spline; I believe your 96 will be 27 spline my 98 was). If your 233 is 32, you will probably have to get the front yoke off said tc case rear driveshaft.

Lastly, if your 96 has the flat flange type front axle input, you WILL have to have a front drive shaft made. You'll need a driveshaft from a 233 and have the back of that shaft welded to the front of your astro shaft. OR, you can get a front driveshaft AND a front axle input yoke from a later Astro with an NP136 and change out the front axle input yoke on your Astro. You could also use a yoke from an s-10. Note that if you change the yoke, you need to follow protocol on pinion pre-load when you tighten it back up. No big deal, but you don't just "tighten it up".

And then there is the whole electric shift/TCCU thing that I know absolutely nothing about....

In short, we pre 99ers got the short end when it comes to TC swaps, but worth the effort.

[thegreenmachine]

photo van got it right.

ive been researching this swap for a buddy with a lifted 97awd, I figure that if you grab the front and rear driveshafts out of a 99+ it should be okay, I never had to notch the cross member as t-low did, and it took all of about 2 hours to swap into my 03,

[chuck.z]

Hey all, thanks for the replies. I've been following both of your build threads and they have been inspiring. Lots of custom work on photo_van's hybrid system and very resourceful use of rachet straps on thegreenmachine's build. I'd love to be part of the 4x4 club one day.

It never occurred to me grabbing the drive shafts from the 99+ model may be a bolt on. I'd have to look into that. Can anyone confirm? Also from what I see, Lifted used a 2000 TC as did thegreenmachine. TLow used one from an earlier model (I think from mid 90s) and had to notch the cross member. That brings me to another question. Are there any differences in the cross members in the 99+? I'm hoping to do the least amount of fab work, which may lead me to finding a TC from 2000 model year.

There are a few on this board that used a 233 and converted it to manual shift. Are there others that did the swap to electronic shift besides TLow? As I understand it, I don't have a TCCM as the BW is viscous coupled. Would I have to reprogram the computer to make a TCCM compatible? I'm pretty sure I can handle looking at wiring diagrams and splicing things in where they need to be. But if it is software related, that can get tricky real fast.

[photo_van]

The newer front driveshaft will work at the TC end, but not at the front diff. My '98 ( and I believe your '96) have a round flange up front. Newer models (and maybe older?) have a ujoint yoke. Like I mentioned, you could change out the flange with a yoke and it should bolt right up.

I'm guessing the TCCM works independently from the PCM as (I believe) no vehicle input is required for the 233 to operate (unlike newer AWD). The exception to that would be tying into the PCM if you want all four transmission gears available in low range. Again, I'm just guessing on that. And no, you don't have a TCCU in your '96