You can also look at the two tabs at the bottom of the pumpkin.

If its a 7.5 it has "fangs" that look like little fang teeth. If its an 8.5 the fangs are like two littlel blocks.

Or if you don't understand my way, go to maliburacing.com then go to tech then "7.5" and 8.5" Rearend comparison" It shows the pics of the three and you can also tell the difference by appearence not just by measuring.