The mole moosher thread got me looking for these pics, but rather than muddying that one up I figured I'd just post it on it's own.
Made this about 3 years ago (pre-tractor) and never did put the door handle on it.
Some progress shots:
Used masking tape to create a cut line guide
Used an abrasive cutoff wheel in an angle grinder to sever the tank end (previous end removal was done via plasma cutter a few years ago) and prepare the tank for mating to the second tank
Used scrap exhaust pipe for the stack (got it free from the dumpster at an exhaust shop - with permission)
Cut out the opening for the top plate
Then welded it in