What is this and why would it be there?

Everything is subjective. It is an auto. Some think 4:10 gear is unthinkable for the street. Me a little bit. The car on the highway can run a bit warm with the 4:10’s. Some think a 9.5 converter that stalls somewhere around 3500 rpm not street-able, but the new converters are not like the old “ it won’t even move until I’m at half throttle” my 9.5 converter is fine for me. A pump gas 10 to 1, 4” stroke 3:73 or 3:91 gear would be a GREAT street car. Fine street manors and great longevity and almost quick enough to get you into roll bar territory. Oh I just ran drag week with it and the only change was I went to 3:73 rear gear. To help with the cooling issue. Its 12.2 to 1 so it was boring to drive after I ran through the c12 that was left in the car from racing and was running on pump fuel.