2892513 aluminum BB belhousing

I have two of these belhousings. One of them has an additional bolt boss welded on, see pics.

What do you suppose this was for ?

Maybe for a BB 4-speed deal in an A-body ? I don't know. Maybe something totally different ?

I thought the -513 bells were B and E body bells.

I have a 1969 Dart GTS H code 4 speed car that I took in trade years ago minus the motor, trans and bell housing, flywheel and clutch linkage.
I ended up using a 1965 cast iron stock Mopar bell for the 383 and 361 B motors to use the 10.5 inch flywheel, clutch and replica clutch linkage in it to drive it on the street, it works and fits well: up:

Check the date code. That may help. I bet the blue one is cast much later.

I can't read the date codes, but the extra boss is welded on, not cast in.

Welded in = modified.

OK.
Of course it's modified.
My question is: Does this modification look like it might facilitate something obvious, for example, use in an A-body instead of an E-body ? Use of a particular bracket ? Someone added it for a reason, what might that reason be ?

Of course it could be just a one-off non-predictable modification.

No need for the boss in an A-Body application, no idea why it is there...

The lower welded-on boss could be for a hydraulic slave cylinder.