How to Identify front axel?

I have an 89 f250 4x4. I know what my rear axel is, it is 4.10 limited slip. I was wondering if anybody knew where to get the info on what the tag codes mean for the front axel. I have the codes but cannot find a chart as to what they meen. If you know please email me at brownfam@centurytel.net Thanks guys.