Advice on removing heater flapper boxes
 

The flapper boxes on my '75 are corroding and I'm attempting to remove them. Anyway, I've got the bottom two nuts off but I can't get to the top bolts with a wrench/ratchet/any other tool I've tried. Is there a special tool for this?

Reach in with a 1/4 drive and you can get it but it is liable to snap off..but you still have the 2 bottom.
Bruce

3/8" drive 10mm swivel socket on a 6" 3/8 extension.

Thanks guys, I've been using PB Blaster liberally and hopefully I can get it off without snapping. Drilling for an E-Z Out would be tough in such a tight location..