Boss hog outlaw wild boar torque converter.

My buddy will sell his 3,500-4,200 torque converter but after looking at it it has 10" bolt circle with 5/16" bolt holes wtf? Who would make a high stall converter like that with 5/16" bolts?
I just bought an Boss hog 3200 - 3500 nitrous converter from them about $700 they must have upgraded the bolts this one has 7/16 " & anti ballon plate