Quote Originally Posted by GoDadGo View Post
I'd go with the .64 overdrive with the 3.55's if you expect to do a lot of Highway/Interstate Cruising; however, what is the operation range of your engine, specifically lower RPM range of your camshaft and intake manifold?

To give you an example, my camshaft operation range is 2,300-6,500 RPM with my intake manifold a tad higher. The good news is my 5th gear will get me to 70 MPH @ 2,600 RPM and I can't grab 6th because it drops the RPM down to about 1,750 which will lug the engine.

That's The Big Deal To Answer Your Question!
Go Dad Go

I am doing some research on diff and trans ratios compatibility. What caught my eye was your comment of your cam range of 2300 to 6500 and your inability to grab 6th gear as the rpm will drop to around 1750. At that rpm you begin to experience engine lug. Are you suggesting that in any gear, you can experience engine lug below 1750 rpm with your engine/trans set up.

Background: my set up is a tko600 .64 overdrive, 351w/427 stroker, 2015 IRS mustang 3.31. After extensive professional tuning, I continue to experience engine lug when cruising in any gear between 1,000 and 1800 rpm. And I'm wondering whether my semi aggressive e comp cam is the culprit?

Thoughts?