transmission pan gasket
If you are good with tools, you could buy what is called a HELI coil kit. You will need one of the bolts to find the right size to purchase (metric or ASE?). When I owned and worked on Corvairs, the valve cover bolts would break from heat temper and I would have to do this. The head was alumimun and would strip out easy. The tool comes with a tap to thread for the new coil. Then you would screw the coil into the hole and you have the same size thread of the other bolts. Do not forget to move the little metal spaces from the old gasket to the new gasket. While you have the pan off, change the filter and fluid. there is a file on the Yahoo Rialta-Tech site that tells how to adjust the trans fluid for proper fill. You might also want to think about installing a trans cooler while you are doing this work. The Rialta transmission is a weak link in the drive train.
At the end of your messages it is best to state year & model of the R, as there are differences for solutions.