it says s13 redtop in his build list. Im going to go ahead and assume the tranny is not a s15 6 speed because people really dont do that. there is not really much diffrence between the KA, SR or RB20 transmissions.
i almost forgot to add that the build is looking great. Im personally not into the whole stripped interior/racing seat thing but you can not deny that its gonna move once its done.
Jimmy