Rear Axle Housing Question

[jac04]

Are the Series IIA (p/n 549021) and Series III (p/n FRC3367) rear axle housings interchangeable? I know that the IIA housing has the reinforcement web on the bottom of the 'long' side, which is not present on the SIII housing, but other than that are they the same?

I'm looking into picking up a IIA housing to replace my SIII housing, but I want to be sure that it will work.

Thanks,
Jeff

[I Leak Oil]

They are interchangeable provided you're putting an 88" axle under an 88" truck or 109" axle under a 109" truck. Check the reinforcing member on the axle as they tend to hold moisture and rust the axle tube itself.
Jason T.

[dmurrell]

The only other thing IIRC is the brake line bracket is different between the two, but can be modified to work relatively easily.

[Broadstone]

I find it funny you should ask this question as I just registered for this forum today to ask this question. I have (what I was told is) a NOS 88" rear axle that came with a load of parts a few years ago. I just started building the truck (74 NAS Ser III) last week. This axle does not have the channel axle support under the left side. I would like to know which models and years, and or markets had that channel support and which did not? The number is clearly visible on this axle and is there any way to find more info about which model it would have been produced for? My other 88" ser III rear axles have the support. Thanks and look forward to finally becoming a productive member of the forum, not just a reader!!

[jac04]

I have (what I was told is) a NOS 88" rear axle that came with a load of parts a few years ago.
If you have a FRC3367, please let me know via PM if you would like to sell it. I'm getting a shipping quote from PA Blanchard to have one shipped from the UK, so you can see what one is worth to me.

[jac04]

I also realized that the Series III FRC3367 case has a fill plug in the cover, where the Series IIA does not. Looks like I need to go with the SIII case since my diffs don't have fill plugs.