slant bellhousings

Agree with all the above, and I will add this:
You say your 833 is a '67 or '68; figure out which it is. The '67 will have the small output spline (same as a 904, and I believe your 3 speed), unless it is from a 383 car (unlikely). The '68s (and '67 383 units) went to the larger (727) output diameter and spline.
You should be able to use your current driveshaft if the 833 is a '67, you'll have to change your slip yoke if it's a '68.