Inter diff ratio

Gday. looking at an International diff on Ebay that seems to be from a 1300.
The seller is pretty vague with his discription and only discribes it as being from an AB D line truck, no size.

What I am wanting to know, is there any markngs on the outside of a diff centre that indicate the ratio.

I had a mate that rebuilds diffs for a living tell me years ago that the numbers on the end of the pinion shaft are the crown and pinion tooth count but the diff I had at the time didn't work out that way. I can't remember what the numbers were now but they made no referance to a diff ratio.

Any ideas????

Cheers. Cobba.

hi cobsta my info tells me its an RA15 unit @ 4:88 ratio me thinks on 7.50 x 16 tyres your cruizin @ about 80 k's