weld

I'm about to make a start on my frame brace bars. Concern is my weld on mounts may interfere with motor removal. Any recommendations ?

I pulled a few threads from my bell housing the other day installing a cummins into a NV4500 in my E350 fummins. I can (should have) replace the bolt with a longer one and use the 1/2" of remaining good threads which were tested to 30' lbs. But Id like to insure I wont have a problem again...

Can and O2 sensor be welded in near the end of an exhaust system or does it have to be right on a primary near the engine where it is hottest? I've always had the impression that O2 sensor need to be very hot to operate correctly but my exhaust is ceramic coated. The "muffler" at the end isn't...