Are these lateral caps covering the openings where the axle splines engage?? I've not seen those.

It's in there as we speak. Drives like a dream.

Yes, the lateral caps are where the axle shafts slide into.

According to the FSM 35-500 "Differentiating characteristics, differential installation survey", only the 123 and 107.022/042 starting Feb 1981 and the 126.02 had the small center piece without the lateral bearing caps.

I guess I'm curious to find a gasser with a 2.47:1 rear differential that is a direct replacement.

Well, this now begs the question as to how Breckman and Company managed to put the 2.47 into the SD's????

The FSM lists the 126.03 and 126.04 as having the case with eight lateral bearing caps. I list the following as either an .03 or .04:
84-85 380SE
82-83, 91 380SEL
84-85 500 SEL
82-83 380 SEC
84-85 500 SEC

They all had the 2.47:1 rear end, according to the FSM.

I list the 81-85 300SD as a 126.120, with a 3.07:1 diff.

If you want me to email you the PDF's, let me know. It's entirely possible I've made a mistake in my research.

Those make perfect sense, but, I'm positive that Breckman......et al.....used a 2.47 from one of those gassers. Maybe you can PM him and he can reply on the thread.

Will do.

Breck used a differential with the 8 bearing caps. It seems like I was relying too much on my measuring tape and not enough on just trying it. Breck indicated that the axles slide enough to take up any difference.

I guess I'll get back underneath and try it again.

That's good news. I figured he had a way to use the standard 2.47.

Brian,

Here is the original post from DieselGeek
http://www.peachparts.com/shopforum/showthread.php?t=115889&highlight=differential

I think I have the correct diff - I just didn't go far enough in the process. They even talk about two sizes of differentials in there.

Yes, I forgot about that one. The diff is clearly a bit larger..........but it has to fit.