ok i ordered a dana 44 off ebay to do a temporary fix for the m20.
when it got here it loked like a 19 spline model. yuk.
so i opened it up to look at the spider gears and count the grooves. its dark and oily in there (obviously) and i cant quite get the grooves counted obviously there are more that 19 so its either an offset 30 spline or a 27 spline. the 27 should be a 2-piece axle right? the 30 is a one piece.
so can i just take off the drum and and look at the outer part of the axle and see that there is no nut on there and assume its a 30 spline?

no need to remove drum, if it has a nut holding the hub on it is either 10 or 19 spl. If it has one piece axles its 30 spl. Off set one piece rear 69-71.