Well after 451k the left rear axle bearing has started to grind and the shaft is bad too. While I'm on my third RRear axle this left side will be the first. My axle is 8.8 3.55 gear. I'm looking at E69z-4234a , dorman 630-230, or motive gear1456 as part numbers. Info shows 7.5" as those part numbers. Can anyone verify before I order. Engine is 4.0

 

Could be that both the 8.8" and 7.5" diffs used the same axle shafts. Maybe you can check with your local dealer for part numbers for both diffs.

 

Probably what I would do. Is the Ford number discontinued? Call the Ford dealer with the VIN in hand and ask if the axle is available. If it is not, politely ask him to give you the Ford part number that he says your van needs. A lot of your part stores can give you the direct cross-reference of what they sell by entering the Ford part number.

 

Ford Truck Replacement Rear Axle Shafts | Sierra Gear & Axle


https://www.yukongear.com/ProductDet...px?ProdID=1157

 

Quick update. For some reason the 8.8 and 7.5 axles are the same. I ordered the motive gear 1456 from Summit and did the axle, bearing and seal. Upon inspection the bearing had ground the shaft leaving a sludgy metallic type paste in the bearing race. I had to transfer the studs. Used Harbor freight bearing puller set and slide hammer.

 

So I'm guessing that the only reason they would be different is if one shaft would be thicker (31 spline) than the other (28 spline). I don't believe the Aerostar ever got the thicker splined shaft.

 

In the Ford catalog it lists the E69Z 4234-A shaft for both the 7.5 and 8.8 locking and non-locking diff's 91-97.