What Diff Is This?

[Glenn]

I found a differential in my stash of parts and not sure exactly what it is.

It's IRS and has 4 spyder gears. There's a VW part number stamped on it 113 517 135.

It looks like a stock VW diff that's been modified to accept the extra spyder gears.

[Billyisgr8]

That looks like a Transform unit, I have one too..  Does it say Transform,  patent pending on it on the nut...could have been on the diff too, I can't remember?  The welded nut broke loose on mine and had to be re-welded.  Don't know if it is stronger or weaker than a new one though.  Mine has held up pretty good pushing a super beetle with a 120 hp T4 , I droped the clutch many times expecting to break the stock diff,  When I took the tranny apart this was in it.  

Maybe Bruce can chime in about strength.

Kevin

[Bruce]

The pro trans guys don't like those diffs, probably because they see lots of them busted.  But they also see lots of aftermarket superdiffs busted too.
The one good thing that has going for it is that the cast iron used by VW is wayyyyyy better than the crap iron used in a supediff.  The only problem with the design is that they have to weld that bushing onto the side of the housing for the extra shaft.  That's where they break.
I can't tell from the pics if the diff has 15 tooth side gears or 17 tooth gears.  If it had the stronger 15 tooth gears, I probably wouldn't discount it's strength too much.  Got a closer pic of the splines sticking out?