D-150 8-1/4 Differential

Yup. Axles from one d150 8-1/4 will swap into another D150 8-1/4 housing no problem

Never heard of 5 on 5 in anything Mopar older than a 99 grand Cherokee. Sure they ain't 5 on 5-1/2?
How are you measuring? What's it out of? Year?
5 on 5 has always been associated with GM. They had 5 on 4-3/4 and 5 on 5 for years.