10 bolt and 12 bolt widths and gear ???'s

[glock35ipsc]

I have notes that say the 12 bolt is 63-5/8" between axle flanges.  Is a 10 bolt the same?

Also, the 85 1/2 ton I am getting has 2.73's in it.  If I remember correctly, the lowest gear I could swap to would be a 3.42 before I would need to change carriers, is that correct?

[HAULIN IT]

Not positive about the exact width (down to the 5/8" part) but they interchange as a swap, they are very close if not identical in width.
 The '85 should have a 8.5 10 bolt, they have a very large case spread...2.47
& down is one & 2.73-up all use the same from what I recall. Someone else may be able to give you confirmed info. Lorne   

[glock35ipsc]

Sorry, forgot to add that it has the original 10 bolt.