Jag IRS Differential cases and stub axle seals

[Buzz]

Hi again -

I finally got the drive axles and lower arms from the "new" 3.31 IRS assembly shortened to spec. The machinist did a really nice job beefing up and balancing the shafts and I'm just waiting on the new U-joints to arrive so I can start reassembling.


I went back and forth on which differential I was going to use and had settled on the 3.31 because it just looked that much better and in better condition once I got it degreased and power washed. Both are Powerlock units and I figured that the 3.31 ratio would work a bit better in 4th gear since I rarely shift into 5th in normal driving on our hilly, twisty roads.

Once I opened up the case though, the old fluid was very milky and there were bits of thin, rusted slivers of metal in the bottom which I figured could be from the clutch pack. The assembly turns smoothly with no play or noise, but it looks like it has been waterlogged and I decided to set it aside for a future full rebuild project.

So now I've disassembled the old 3.54 unit and cleaned a bit of the gunk off of it. The fluid is clear and clean and it turns smoothly and silently with only a very tiny bit of play at the pinion. The only glaring issue is a leaky stub axle seal on one side.

The cases are both markedly different - there's a lot of conflicting information out there on positively identifying the series and vintage, but due to the botttom drain plugs on both, I know that they are both Salisbury units. The brake calipers appear interchangeable and both bolt in from the diff case outward, but the stub axle flanges and the cases themselves are different. I've attached some pics in the hope that some of the gurus here can ID the 3.54 unit so I can order the correct axle seals.

Below are the flanges side by side. 3.54 case on the left is gold below all the other stuff and the 3.31 on the right is originally red.


Here are the two cases. First the gold 3.54 with the reinforcing fins.


Next is the 3.31 case with solid bars instead of fins.



I've done a lot of checking around the various sites and forums for info, videos and photos, but I'm still not 100% sure what exactly I'm dealing with. I'd really appreciate any help in establishing what seals I need for the 3.54 case.