[ANILE8]

Yes, it is possible and I have seen videos of it being done that way but I would not have liked to do it. With an impact gun, it literally takes less than 10min extra to drop the driveshaft.

Also because I was installing the DSSR I needed to see the alignment with the shifter rod to know how much to bend it and not removing the driveshaft would have made that virtually impossible.

Either way, installing the bolts from underneath or above makes little difference. Installing from above you can do it all yourself with a pair of vice-grips. Also, I didn't want all that extra bolt length sticking up through the trans tunnel. Cutting a bolt down is really easy or you can just use a shorter bolt.