help identify this transmission. Supposed to be A518

Hey guys
I picked up this trans second hand down the road. It was advertised as a A518 with a lock up convertor. It has the 3 pin plug so if it is an A518 it must be a RH model. It looks just like my other A518 I have except it has a weighted converter and an offset converter bolt hole like the 360 LA converters.

I was always under the impression that these transmissions came out behind the 360 magnums which are weighted on the flexplate like mine and the converter is neutrally balanced. It has 064-3 as the casting number. Also noticed it has an electronic speed sender.

Can anyone please tell me if it is actually a 518? If it is I could cut the weight off the converter but how will I know if its a lock up or not. Is there anyway to tell by looking at it?
Maybe these came out weighted behind a different engine I am unaware of.
thanks Maca