Mine looks like cheap garbage next to yours, but it's infinitely better than the way it came out of the car! I had only two hours to clean it and paint it before hauling it to have it put in my car. Then I found out it's a 6.7 and not a 7.5" like I needed. Yay.
Looks like the diff could have been identified by the rear cover differences. Among other design differences on the housing, between the 7.5" and 6.7".
The rear diff cover on that one there is way different than the 7.5".
Absolutely. However, I freely admit to being a noob about the differences, and having been told "This is an 85 Celica 7.5 diff" by someone with what I presumed was better knowledge than me, I didn't know any better. Having seen them both now, I'd not make this mistake again. =)
I also want to mention that this was for sure an honest mistake by both parties involved - not someone out to deliberately screw me over.
My hope is that people visiting here can avoid the same issue!