Chevy & GMC Vans

So i have found parts of this info posted in both axle posts and brake posts but no definitive answers so i apologize if it has been covered somewhere.

So the question is will a 1998 axle bolt up to my 2004 astro?

The source of the question is this. I really wanted to find a van with 3.73 gears in it when i was buying mine. Alas i never found one and settled for 3.42 gears. I now have 31 ish inch tires on my van and am dying for lower gears. I know i need 4:10 gears down the road but the cash is not in play at the moment. I found a 1998 low mile van at the junk yard with 3.73 gears. I can have the front diff & rear axle for $265 bucks seems like a great price for a half step that will get me by for a year or so.

My concerns are these

1. I know it used disc instead of drum but that appears to be bolted onto the square flange on the axle. does this bolt right up?

2. I failed to check, but my research seems to show 2 different lug patterns. is this the case with the years in question? And if so could i use my inner axle half shafts inside the older housing....are the splines the same?

3. any thing else that i am missing.

I plan to go back to the junk yard and take some more measurements tomorrow but wanted all the info going in as i could have.

Ryan

I don't know for sure if the rear axle will work but I suspect if you swap the axle shafts and all brake parts it will work fine. The front is easy, just use the 04 CV half shafts and the 98 front diff will bolt in. They are a direct swap as far as I can tell. Yes, you are right in that the bolt pattern is different between the 98 and 04. Any chance that 98 has a G80 posi? If so grab them and worst case you could install the 3.73 gears from the 98 housing into the 04 housing.

LiftedAWDAstro wrote:I don't know for sure if the rear axle will work but I suspect if you swap the axle shafts and all brake parts it will work fine.

I will do a little more measuring today and see what i can come up with. I might take a chance and then report back if it all looks good.

As to the g80 no....i read through the rpo codes 6 times making sure i hadn't missed the g80 but truly it wasn't there.

One last question for you lifted. Going back farther to when these things had stock 4.10 gears is there anything that is compatible.... With the final generation?

Thanks for your time. Again i will report back when i know more.

Ryan

The 4.10's from the early vans will work but only the ring and pinion unless you can find one that takes 28 spline axles and then the carrier will work too. Before about 1990 all axle shafts were 26 spline.

i have been considering the same swap myself. i aslo have 3.42's and 4.10's are a little out of my price range.

LiftedAWDAstro: shouldnt you be able to pop the diff cover, remove the axel clip things, and slide the 6 bolt axel into the ummm axel? If your picking up what im putting down?

Im intersted to find out.

I am getting what you are saying. I gotta think the housings and axle tubes are the same dimensions and yes you should be able to simply swap the axle shafts. I don't know for sure if they are the same dimensionally or not with the only difference being the lug count. I have never done it though and I scrapped a set of 5 lug 28 spline axle shafts a few years ago. ](*,)