I've never heard of someone going from 25 to 20 on tranny. Most of the time its just that shady importers put 20 trannys on a 25. The 20 is a weaker transmission. I guess going to a 20 you could use the stock KA driveshaft yoke but I wouldn't ever want to downgrade just for the driveshaft.I've seen a few guys switch the rb25 trans for a rb20 trans on the rb25det's and was curious if there is any advantage to his? I have a full rb25det swap that came with an rb20 trans so i'd like to know what the differences are if any.