When I installed a Platinum LSD tranny in my 84 GTV6 we (RJ & myself) replaced the isostatic imput shaft with one from a GTV6 tranny. There was no need to weld anything. IMO the early GTV6 shifter is preferable to the Iso type and I had two Milano's.
Yes sorry! its an 84 GTV6. I am new to Alfas, so I am not well-versed on what they may have been trying to accomplish. Sadly familiar with "Previous Owner Syndrome" that we see all the time in my shop. With the early 911's though, I already know what to look for and can deduce what someone was trying to do...Flying blind with this at the moment, but learning is the joy