Reaper19

I have an opportunity to obtain a rear diff and batwing that has been rebuilt with 3.07 gears and only 3000 miles on it. I currently have the stock 2.87 gear ratio in the car with an automatic tranny (TH350C) and do not believe the diff has ever been rebuilt with 100,000 miles on it.

Just wondering in anyone has performed this upgrade?

Any issues with the 3.07 ratio and TH350C, other than higher RPMs at cruising speed?

Is the switch over worth it?

I may also pick up a brand new 2004R tranny to install that also has been been billet built with no miles on it. So the tranny is way more built than I need for my little over stock performance enge, but could possibly get it at a good price with crossmember. The torque converter may have a too high stall at 2600-2800, but that can be changed.

Thanks

JimLentz

If you go with the 200 4R you might want to consider something like a 3.55 rear axle. That would give you decent low speed torque multiplication and wouldn't rev too high on the highway.

Big2Bird

3.07 with an OD tranny is a nice upgrade.
I have the same with 700R, and it cruises nicely.
At todays gas prices, it's a win win.

JimLentz

The 700 has a 3.06 first gear ratio and the 200 has a 2.74 first gear ratio. I calculate that a 3.43 rear ratio with the 200 would run similar torque multiplication to your 700 with the 3.07 rear axle ratio.

The 700 has a .70 OD ratio and the 200 a .67 OD ratio. This means a 3.2 rear axle ratio with the 200 would run the same highway RPMs as your 700 with the 3.07 rear axle ratio.

The 700 has a wider 1st to 4th gear ratio spread than the 200.