anyone know any easy way to weld an automatic 86 accord's differential?

as far as i know there is no easy way. the tranny has to come out of the car then it has to be taken apart to get to the differential then welded. then put everything back together.

technically - its not legal at the track, just so you know.
realistically - be careful your welder knows what he is doing. most people who just go in there and gob it up with weld learn a quick lesson in heat treating upon the first launch.
remember that if you break the diff on one side alone your car will become one wheel drive and fall in love with the wall.

It's possible but not easy a sand tank or a oven would be required for cooling.