My 83' TA is mechanically original and only has about 60k miles on it. I'm just now starting to mess with the car after having it 6 months or so and I noticed there were two wires under the dash not connected to anything. I traced them down to this box which is T'd in with speedo cable at the transmission. I'm guessing its some sort of adapter to change the speedo gearing because someone had bigger wheels and tires on it. I'll be going with stock size tires. I'm thinking I can just yank it.

 

That's what it appears to be. Bigger tires or the rear end was swapped out and was equipped with a different ratio than the OE. If the latter case, you'll have to swap in drive and/or driven gears.

JamesC