The Stovebolt Site Forums The Shop Area Driveline Swapping AD to open drive

I think in all fairness a rough cost comparison of the basic mph/decreased rpm's are in order.

From Patricks site the 3.55 conversion is about $1000, shipping included, you will be doing all the work. This method can pretty much be done in a weekend. I expect some feedback here.

For my 3.90 conversion, the center section was $125 from a boneyard, another $200 for the bearings for the axles and differential, crush sleeve, etc., $100 for the open driveshaft, $125 for my Borg-Warner 3sp+od, $75 for it's rebuild kit, $25 for axle saddles and another $25 for the spring relocation kit, for a grand total of $675. I wasn't by far the first to do this but acquired my knowledge from an incredible source...Jack Halton, past president of Inliner's International who made bi-yearly trips from FLA to VA-PA in his beloved GMC with a 302 ci and the aforementioned drivetrain combination. I was lucky enough to call this man friend.

The extended 3.90 method with overdrive will take much more time and without hunting down the scarce getting scarcer by the day Borg-Warner 3sp+od one can now go to a T-5 which is stout enough for our trucks.

With the above combination .70 overdrive and 3.90 rear my rear end is at 2.73 in 3rd overdrive, 70-75 mph is at 21-22 hundred rpms, a delight to drive on long trips and economical as well.