Guts are the same, you must change the input yoke from the flange (Riv bolts to a double cardon joint ) to yoke. Here is a Riv driveshaft: you can see it has a flat flange vs yoke on yours.
Thanks guys! No, I'm not looking for posi. I just removed one from a Riv I stripped and since I'm going to a 4L60E overdrive transmission I thought I'd try and see if I can get some more bottom end. Now I just need to figure out RPM at cruising speed....
The standard STOCK ratio on most '64 Rivs. are 3.07. In O/D with a 30% reduction would be about a 2.15-1 ratio. Kinda low unless you want to cruise at 80MPH at around or under 2000RPM's.
I ran all the numbers through a calculator and with my tires, 3.23 rear gears and an OD ratio of .696 I should be at about 1800 rpm at 70 mph. First gear is quite a bit lower on the 4L60E than on the TH400 so I should have more jam off the line too With the stock 3.07 gears and th400 I would be at 2500 at the same speed.
That's easy. 336/tire height X final drive X MPH = RPM (no converter slip) The 4L60E has an OD ratio of .70, so multiply your rear gear by that to get final drive. Using my car as an example. I am running 28" tires, 3.73 rear gears. The Gear Vendors adds an OD of .78. Final Drive is 3.73 X .78 = 2.91 At 60 MPH, 336/28 X 2.91 X 60 = 2095. My actual RPM ends up a bit over 2200 RPM due to converter slip.
Whenever changing rear end/driveshaft parts, be aware of the clearance for the nut on the pinion gear yoke. I had a helluva time getting my new custom driveshaft to fit without hitting the edges of the nut once the car was back on the ground.
