Diff Swap Help

[808ETA]

My diff swap is turning into a can of worms. I bought a 3.45 open diff from someone however I'm not 100% which car it came from. I believe it's either a z3 or 318ti because the differential flange cover has the thinner o-rings and the output shafts are the shorter “dumbo ear” style. When I bought the o-rings and output shafts the part numbers showed a range of years and models. My car is an 84 ETA and my speedometer pulse sender plug has a different connection. Since the pulse sender is shorter in the 3.45 diff I'm not sure if swapping the cover will work. Is it possible to solder in a late model pig tail? Any help would be greatly appreciated. BTW the diff looks to be the same size and dimensions to bolt up.

[808ETA]

So the diff is from a 318ti. Still trying to figure out if I need to swap the diff cover or just change the pigtails

[bmwman91]

See if you can get the old pulse sender to work in the new cover first. If you get a speedo signal, then it is fine. You can always put in the 318ti sender and splice the connector on after everything is reinstalled.

[808ETA]

See if you can get the old pulse sender to work in the new cover first. If you get a speedo signal, then it is fine. You can always put in the 318ti sender and splice the connector on after everything is reinstalled.

Thank you for your help! The old pulse sender is actually longer and bottoms out. My pigtail just came in so I will probably just splice it.

[808ETA]

Update. Got it in and it makes a big difference over the 2.79 that came in. I used the 318ti diff cover and speed sensor. I just changed the sensor pigtail on the car.