I'm fairly certain. It makes sense that the ratio is paired to the transmission gearing. I'll look for some corroboration.

 

Dave, I'm no longer certain. Checking 3 different sources, none of them are consistent with the others. If we could get folks with 340 and 380, MT and AT cars to report back what their engine speed is at 70mph in top gear, we can do the math. Top gear on the AT is 0.67:1, and on the MT 0.85:1. I'll post the 380MT number tomorrow, but I believe it's right at 2500rpm.

 

Here is a reasonably priced T2R4000.

https://www.ebay.com/itm/Rear-Axle-D...UAAOSwk9xeXm3X