If the hold down studs are original steel ones, then buff them over especially the threads themselves, then lay them out and paint them end for end with some silver engine enamel spray........If stainless then just visually check the threads for any sharp burs/edges, perhaps lightly buff the threads anyway........no paint necessary.......Lock 2 of the 1/2" BSF thin nuts 879 together on each stud........coat only the upper threaded section of the lower thread with your choice of sealant..........wind each stud into the holes and tighten with a ring spanner 13/16" will work fine, with length not more than 300 mm, with normal hand strength up nice and tight.........no torque wrench needed..........swap the nuts to the next stud and repeat over. Wipe away the excess sealant at the base of each thread. Do you have all the bearings, oil pump sleeve, and spindles in the cases at this stage...........?..........You should fit the output shaft seal, the shaft itself with the 3 rd gear and spacers, sprocket, seal cup and nut before installing the G 50 plate.........Make sure the bushes in the output shaft are in good order with some running clearance.........new bushes tend to shrink a bit when they are installed thus need to be reamed out to suit the input shaft sizes..........The shaft should spin freely with the slightest of play felt.........never run them tight, as they will quickly destroy themselves, especially the large inner one the G 16.