1991 mustang t-5 trans speedometer gear and opinions on current gearing

so im taking apart my 91 mustangs drivetrain as we care building the engine in the process of taking the trans out right now and i see that the gear is redish color (i added a pic attached) im also adding a pic of what the speedometer is reading when im drving 60 mph. im hoping with these yall can tell me what gears are in the car or guess, while i have it all apart id like to get the speedo reading correctly, also its oem tire size as well. also the needle kinda dances a little bit when below 20 mph im thinking a new cable will fix that but i dont know what to do about the speedometer being off so bad