This looks like a good value for synthetic gear oil:
Lucas Oil 10123: Synthetic Gear Oil SAE 75W-140 - JEGS High Performance (https://www.jegs.com/i/Lucas+Oil/639/10123/10002/-1?gclid=EAIaIQobChMI_qvmovTJ_QIVHPLjBx0Oywd9EAQYAyABEgKBP_D_BwE)
I've read that many use 80w140. This is 75w140. Any opinions on whether that would matter?
I've also read that the rear end takes about 4 gallons and each hub around a quart so it seems like the right amount.
Won't matter.
jk