"With 3.08 :: 1 gears in the diff you can’t use OD at all. Your engine rpm at 60 mph would be 1600 rpm. Most gas engines barely make power down that low. You could use the 700 R4 if you change your gears to 3.42, 3.73, 4.11, 4.56, 4.88, 5.12 or 5.30."
Looks like I will have to up the diff to 3.42 or 3.73. He likes the 700 R4, why?
I think your tranny builder is correct. I would not put OD trans in unless you have gears in the 3:42 range or higher. I put a 2004R after I switched to 3:73 gears and it dropped my highway RPMs from round 3200 rpms at about 65 to right around 2100 RPM's. The 700R4 takes more to make it work in the FB. You will need an adapter plate to mate the trans to your engine (unless you have a Chebby engine...lol) and a computer to run it. You will need to shorten your driveline, but then again had to also since the th400 I was replacing was about an inch longer then the 2004R. I also believe you will need a new trans crossmember but you wouldn't need a new one if you put in a 2004R.
