Shimano dura DI2 ace shifter/levels

right guys need your help if poss
just bought a new argon e-119 TRI BIKE with di,but no shifter on brake levels so looking to upgrade to full di shifters
ive got given a dura ace break/shifter st-9071 right side then i manged to buy the left level which i thought was the same its a dura ace st-7971
now the problem is the 9071 wire has 1 pin plug and the now i know older model 7971 has a 4pin plug in the wire.
so the question is,is there a way to join these two up with a converter etc ,as this is now a bit out my depth and me mechanic had a hoff
thanks for your help in advance or am i going to have to buy a new left level
just bought a new argon e-119 TRI BIKE with di,but no shifter on brake levels so looking to upgrade to full di shifters
ive got given a dura ace break/shifter st-9071 right side then i manged to buy the left level which i thought was the same its a dura ace st-7971
now the problem is the 9071 wire has 1 pin plug and the now i know older model 7971 has a 4pin plug in the wire.
so the question is,is there a way to join these two up with a converter etc ,as this is now a bit out my depth and me mechanic had a hoff

thanks for your help in advance or am i going to have to buy a new left level
0
Posts
If the software is up to date and you could just use the RH brake shifter in synchro-shift mode and not bother with the LH shifter - this is what I do
You''ll also need a junction B box to to connect to your existing system (unless it already has a 5-port Junction A)
thought it was as much
got a new left hand one if you like (four pin)for sale