On my W123 body (Diesel Motor)

Crack approx. 2 “ length has been found on
big cross beam.

This big cross beam is welded between left frame
and right frame and located under engine near oil reservoir.

How can I repair this crack by gas welding?

I think electric arc welding is not acceptable because
may be arced between engine bearing and crankshaft or on bearing wheels etc.

see my reply in Diesel Discussion.

Best of luck,