Good day,
Yesterday I was working on the 4Runner after failing the emissions test the previous day. As a precaution, I purchased a new cat just in case (after all it does have 315,000 on it) I PB Blasted the 4 bolts and let them soak while I changed the oil, filters and cleaned out the TB. I then moved under the truck and found a 14mm was the correct size and loosened the two front bolts with little effort. When I went to the rear bolts, the 14mm would barely garb the bolt head and not wanting to booger them up I grabbed a 13mm. It was too small, so I went to a 1/2 and 9/16 with similar results... WTF? So what size are the two rear bolts, 13.5mm? (haha) Both bolts are in good condition, no rounding of the corners and appear to the same as the front two... Any ideas? The vehicle is an 89 4Runner, 3.0.
Thanks in advance.
d.

 

All 4 should originally been the same. Some might have been replaced at some time in the past with SAE bolts.

Try some fractional inch size tools. 6 point stuff is always best.