The pics in his OP show the "z28" stripes, so I'm presuming it's a T Code Type LT which would explain the Turbo 400.I’m surprised it has a th-400. I had a couple 74 LT’s with 350 4bbl and both were th-350’s. With that low of mileage I’d leave it alone or swap out the mtr trans and driveshaft, if I wanted to get more perf. Does it have a limited slip? These cars are getting more popular. And all original will get you the best return on your investment so having an unmolested power train with an oddball (very cool) # matching th-400 will be a premium on resale.