1965 904 Real Seal: Can it be change in car?

The longer the '65 Formula S sits idly by in the garage without running, the wetter the floor becomes directly under the rear seal at the end of the tailshaft of the original A/T. Drainback from the torque convertor is probably a factor. Regardless, can the seal be replaced without removal of the transmission? Photo shows dry seal before ATF was added. (Driveshaft still bolts to transmission factory style but now his slip-joint conversion from the previous ball & trunion set-up). Thank you.

driveshaft front ujoint 2.JPG

driveshaft front ujoint 1.JPG

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