Russ, assuming the OD setup came from a 64 American the rear axle ratio could be a 3.08 (standard with 196 OHV), 3.31 (optional w/196 OHV), or 3.78 (only one for 196 L-head, also standard w/196 OHV Twin-Stick). Hopefully it's a 3.31. Should be a tag on one of the rear cover bolts, but that might have been removed when it was rebuilt. Odd that they lost that tag and kept the one on the drain bolt though. The problem with changing from the "big nut" driveshaft is the pinion shaft. I'm not sure the splined end is the same diameter and spline count as the later open drives. The pinion shaft also isn't drilled for a bolt to hold the later model yoke on. Any machine shop can remedy the bolt problem, you'll have to check the splines with a yoke from a later model. Check the length also -- the big nut pinion may be a bit longer, but I think it's the same length as a later pinion shaft. The bearing diameters need to be checked also. -- Frank Swygert Publisher, "American Motors Cars" Magazine (AMC) For all AMC enthusiasts http://www.amc-mag.com (free download available!) _______________________________________________ AMC-list mailing list AMC-list@xxxxxxxxxxxxxxxxx http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com