It's got the smaller spline like the stock 56 series 4 speed. The 60 series uses the same small spline. The 63 and 71 series have the larger 510/zcar spline count. I brought the case to a guy that specializes in aluminum case repair. There are some oil slots that keep the seal lubricated. He can't do anything to repair that. The bushing is also toast. I'll post some pics.
I should be able to use a housing from a F4W60A or FS5W60A. Maybe a FS5W60L would work as well.
Thanks,
Pete